{"id":22419,"date":"2026-08-28T07:55:28","date_gmt":"2026-08-28T05:55:28","guid":{"rendered":"https:\/\/www.curiaweb.ch\/?post_type=docs&#038;p=22419"},"modified":"2026-08-28T07:55:29","modified_gmt":"2026-08-28T05:55:29","password":"","slug":"wordpress-website-nicht-erreichbar","status":"publish","type":"docs","link":"https:\/\/www.curiaweb.ch\/en\/hilfe\/wordpress\/wordpress-website-nicht-erreichbar\/","title":{"rendered":"WordPress website not accessible: systematically check causes"},"content":{"rendered":"<p class=\"wp-block-paragraph\">When a WordPress website suddenly becomes unreachable, WordPress itself does not necessarily have to be the cause. Between entering a domain in the browser and the finished WordPress page, there are several technical layers: domain and DNS, network, web server, SSL\/TLS, PHP, database, and finally WordPress with its plugins and themes.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Therefore, a systematic diagnosis makes much more sense than randomly deactivating plugins or changing settings.<\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p class=\"wp-block-paragraph\"><strong>Briefly explained:<\/strong> First, check whether only you or other visitors are affected as well. Next, pay attention to the exact browser or error message. DNS errors, SSL issues, HTTP 500, HTTP 404, database errors, and critical WordPress errors have different causes and require different solutions.<\/p>\n<\/blockquote>\n\n\n\n<h2 class=\"wp-block-heading\">\u201eWebsite not reachable can mean many things<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">The statement \u201eMy WordPress website is not working\u201c is not yet sufficient for a technical diagnosis.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">For example, very different symptoms can occur in the browser:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Domain is not found at all<\/li>\n\n\n\n<li>Connection timed out<\/li>\n\n\n\n<li>Connection refused<\/li>\n\n\n\n<li>SSL or certificate warning<\/li>\n\n\n\n<li>Too many redirects<\/li>\n\n\n\n<li>Error 500<\/li>\n\n\n\n<li>Error 404<\/li>\n\n\n\n<li>blank page<\/li>\n\n\n\n<li>critical WordPress error<\/li>\n\n\n\n<li>Error establishing a database connection<\/li>\n\n\n\n<li>Maintenance mode<\/li>\n\n\n\n<li>only individual pages are not working<\/li>\n\n\n\n<li>Frontend works, but the admin area does not<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">These differences are crucial for troubleshooting.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">1. Note down the exact error message<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Before you change anything in WordPress, note down the exact message from the browser or the website.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">A screenshot can also be helpful.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Phrases like \u201edoesn't work\u201c or \u201eis offline\u201c contain hardly any technical information. A specific message such as:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><code>500 Internal Server Error<\/code><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">thereby clearly narrows down the possible causes.<\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p class=\"wp-block-paragraph\"><strong>Practical Tip:<\/strong> Copy an error message as accurately as possible. Even an HTTP status code, a domain name, or a few words from a technical message can be crucial for diagnosis.<\/p>\n<\/blockquote>\n\n\n\n<h2 class=\"wp-block-heading\">2. Check if the entire website is actually affected<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Don't just visit the home page.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">For example, test:<\/p>\n\n\n\n<figure class=\"wp-block-embed\"><div class=\"wp-block-embed__wrapper\">\nhttps:\/\/deine-domain.ch\n<\/div><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">a well-known subpage:<\/p>\n\n\n\n<figure class=\"wp-block-embed\"><div class=\"wp-block-embed__wrapper\">\nhttps:\/\/deine-domain.ch\/beispielseite\n<\/div><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">and the WordPress admin area:<\/p>\n\n\n\n<figure class=\"wp-block-embed\"><div class=\"wp-block-embed__wrapper\">\nhttps:\/\/deine-domain.ch\/wp-admin\n<\/div><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">This already provides important clues.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Examples:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Everything unreachable:<\/strong> Domain, DNS, Server, SSL, or a basic website error are all possibilities.<\/li>\n\n\n\n<li><strong>Homepage works, subpages show 404:<\/strong> Permalinks or rewrite rules are suspicious.<\/li>\n\n\n\n<li><strong>Frontend works, login doesn't:<\/strong> The problem is likely more specific to the login or the admin area.<\/li>\n\n\n\n<li><strong>Only one side is defective:<\/strong> A problem with this exact content, template, shortcode, or plugin is more likely.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">3. Check if the issue affects only your device<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">If a website is unreachable on your computer, it doesn't automatically mean that it is down for all visitors.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Test the website if possible:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>in another browser<\/li>\n\n\n\n<li>in a private or incognito window<\/li>\n\n\n\n<li>on another device<\/li>\n\n\n\n<li>via a different internet connection<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">Using a smartphone over the mobile network is, for example, a useful cross-check if your computer is connected via Wi-Fi or another internet connection.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">4. Exclude browser cache as a local cause<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Browsers store certain content locally. In individual situations, this can therefore result in an outdated or incorrect state being displayed.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">A private browser window or another browser can help isolate local browser data as the cause.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">However, this should not be confused with a general problem-solving approach.<\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p class=\"wp-block-paragraph\"><strong>Important:<\/strong> A browser cache does not cause a DNS outage and does not fix a PHP fatal error. Clearing the cache is therefore not a universal first step for every WordPress problem.<\/p>\n<\/blockquote>\n\n\n\n<h2 class=\"wp-block-heading\">5. Check domain as cause<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Before WordPress can be loaded, the domain being used must work.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">In case of domain issues, the following should be checked, among other things:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Is the domain still registered?<\/li>\n\n\n\n<li>Is it expired?<\/li>\n\n\n\n<li>does it point to the designated nameservers?<\/li>\n\n\n\n<li>Are the required DNS records present?<\/li>\n\n\n\n<li>Have DNS settings been changed recently?<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">If a domain cannot be resolved correctly, the request may not reach the web server at all. In this case, WordPress itself can be completely intact.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">6. Understanding DNS: How does the domain find the server?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">DNS translates a domain name into the technical information needed to reach the responsible service.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">For a website, entries like frequently play <strong>A<\/strong> and <strong>AAAA<\/strong> or, depending on the configuration, also <strong>CNAME<\/strong> a role.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">If these entries are incorrectly configured, the domain can, for example:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>point to a wrong server<\/li>\n\n\n\n<li>point to an unused IP address<\/li>\n\n\n\n<li>use different destinations for IPv4 and IPv6<\/li>\n\n\n\n<li>deliver no suitable address at all<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">WordPress cannot fix such a DNS error itself, because the request might not even reach WordPress yet.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">7. Have DNS settings been changed recently?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">If the website is no longer accessible immediately after a change to nameservers or DNS records, this change should be checked first.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">DNS information is cached by various systems. Therefore, changes are not necessarily visible to all users at the exact same moment.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">During a transition, it may temporarily happen that different users still reach different target systems.<\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p class=\"wp-block-paragraph\"><strong>Practical Tip:<\/strong> If a website goes down after a DNS change, do not change WordPress, plugins, and PHP at the same time. First, check whether the domain is even pointing to the intended hosting.<\/p>\n<\/blockquote>\n\n\n\n<h2 class=\"wp-block-heading\">8. Test www and non-www domain separately<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">For example, a website can be accessed under the following variants:<\/p>\n\n\n\n<figure class=\"wp-block-embed\"><div class=\"wp-block-embed__wrapper\">\nhttps:\/\/deine-domain.ch\n<\/div><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">and<\/p>\n\n\n\n<figure class=\"wp-block-embed\"><div class=\"wp-block-embed__wrapper\">\nhttps:\/\/www.deine-domain.ch\n<\/div><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">Both variants must be technically configured correctly if they are to be used.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">If one variant works and the other does not, this may indicate an incorrect DNS, SSL, or redirection configuration.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">9. Detecting SSL and HTTPS issues<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">If the domain is reachable, but the browser displays a security or certificate warning, the problem may be with SSL\/TLS.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Possible causes include, for example:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>no valid certificate for the domain<\/li>\n\n\n\n<li>Certificate has expired<\/li>\n\n\n\n<li>Certificate does not cover a used domain variant<\/li>\n\n\n\n<li>Domain points to the wrong server<\/li>\n\n\n\n<li>HTTPS was configured incorrectly<\/li>\n\n\n\n<li>Redirects between HTTP and HTTPS are faulty<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">An SSL warning should not be \u201esolved\u201c by instructing visitors to permanently ignore the browser warning.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">10. Consider HTTP and HTTPS separately<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">If a website stops working after an SSL change, comparing HTTP and HTTPS can provide clues.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">For example:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><code>http:\/\/deine-domain.ch\/<\/code><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">and<\/p>\n\n\n\n<figure class=\"wp-block-embed\"><div class=\"wp-block-embed__wrapper\">\nhttps:\/\/deine-domain.ch\n<\/div><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">Modern websites should regularly be operated via HTTPS. The comparison here serves solely for technical diagnosis.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">If HTTP works, but HTTPS produces a certificate or connection error, the suspicion falls more heavily on the SSL\/HTTPS configuration than on WordPress itself.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">11. Too many redirects<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Browsers can abort the request if a website gets caught in a redirect loop.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Typical constellations involve, for example:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>HTTP \u2192 HTTPS<\/li>\n\n\n\n<li>HTTPS \u2192 HTTP<\/li>\n\n\n\n<li>www to without www<\/li>\n\n\n\n<li>without www \u2192 www<\/li>\n\n\n\n<li>WordPress URL Settings<\/li>\n\n\n\n<li>Redirection plugins<\/li>\n\n\n\n<li>Server rules<\/li>\n\n\n\n<li>Proxy or CDN configurations<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">If two systems enforce conflicting redirects, an infinite loop can occur.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Therefore, in the event of a too many redirects error, you should check which components control redirects.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">12. Observe HTTP status code<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">When the web server responds, it returns an HTTP status code.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Some codes are particularly relevant for WordPress debugging:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>200:<\/strong> Request was successfully processed in principle<\/li>\n\n\n\n<li><strong>301\/302:<\/strong> Forwarding<\/li>\n\n\n\n<li><strong>403:<\/strong> Access denied<\/li>\n\n\n\n<li><strong>404:<\/strong> Requested resource not found<\/li>\n\n\n\n<li><strong>500:<\/strong> Internal server error<\/li>\n\n\n\n<li><strong>502:<\/strong> faulty response from an upstream or downstream service<\/li>\n\n\n\n<li><strong>503:<\/strong> Service currently unavailable<\/li>\n\n\n\n<li><strong>504:<\/strong> Timeout between participating systems<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">The status code is not a complete diagnosis, but it narrows down the error area considerably.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">13. Error 500 is not the same as website unreachable\u201e<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">At a <strong>500 Internal Server Error<\/strong> the server received the request, but could not successfully process it due to an internal error.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">In WordPress, PHP errors, plugins, themes, among other things, <code>.htaccess<\/code>, memory limits, and other server-side issues.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">You can find detailed troubleshooting at <a href=\"\/en\/help\/wordpress\/how-to-fix-wordpress-error-500\/\">How to fix WordPress error 500<\/a>.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">14. Properly understanding Error 404<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">An HTTP 404 error basically means that the requested resource was not found at the address used.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">When the WordPress home page works, but numerous posts or subpages suddenly show a 404 error, the permalink or rewrite rules can be a potential cause.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">We cover targeted diagnostics under <a href=\"\/en\/help\/wordpress\/wordpress-fehler-404-beheben\/\">Fix 404 error in WordPress and repair permalinks<\/a>.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">15. Error 403: Access Denied<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">An HTTP 403 status means the server understands the request but refuses to authorize it.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Depending on the environment, possible causes may include, for example:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>File or directory permissions<\/li>\n\n\n\n<li>Safety rules<\/li>\n\n\n\n<li>Web server configuration<\/li>\n\n\n\n<li>Security plugin<\/li>\n\n\n\n<li>IP-based block<\/li>\n\n\n\n<li>faulty rules in configuration files<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">Therefore, a 403 error should not automatically result in reinstalling WordPress.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">16. Error 502, 503, or 504<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">These errors differ from a classic WordPress 404 and should not be treated the same across the board.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Depending on the server architecture, upstream web servers, PHP processes, proxy systems, or other services may be involved.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">A <strong>503 Service Unavailable<\/strong> can mean, for example, that a required service is temporarily unavailable or the environment cannot process a request at the moment.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">A <strong>504 Gateway Timeout<\/strong> indicates that a participating system did not receive a required response in time.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">In the event of repeated 502, 503, or 504 errors, the timestamp, affected URL, and frequency are particularly important for the technical analysis.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">17. Connection is timing out<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">When the browser waits for a long time and eventually reports a timeout, this is different from a WordPress error page that appears immediately.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Possible causes include, for example:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Network connection<\/li>\n\n\n\n<li>Server availability<\/li>\n\n\n\n<li>Firewall<\/li>\n\n\n\n<li>overloaded or blocked processes<\/li>\n\n\n\n<li>external services whose response is awaited<\/li>\n\n\n\n<li>very long PHP processes<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">The exact error and server logs are more important here than speculative changes.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">18. \u201eError establishing a database connection\u201c<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">WordPress needs its database for content, settings, users, and numerous other information.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">If WordPress cannot connect to the database, a corresponding error message typically appears.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Possible causes include:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>wrong database name<\/li>\n\n\n\n<li>incorrect database user<\/li>\n\n\n\n<li>incorrect database password<\/li>\n\n\n\n<li>incorrect database host<\/li>\n\n\n\n<li>Database service not available<\/li>\n\n\n\n<li>damaged or manually modified configuration<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">The WordPress database access credentials are usually stored in:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><code>wp-config.php<\/code><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">configured.<\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p class=\"wp-block-paragraph\"><strong>Attention:<\/strong> Change database credentials in <code>wp-config.php<\/code> Not on a hunch. If the values have worked so far and no one has changed the database configuration, it should first be clarified why the connection is suddenly failing.<\/p>\n<\/blockquote>\n\n\n\n<h2 class=\"wp-block-heading\">19. Critical WordPress error or white screen of death<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">If the domain and the web server are fundamentally accessible, but WordPress displays a critical error message or just a white screen, the focus of the diagnosis shifts more toward PHP and WordPress itself.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Common causes are plugins, themes, custom PHP code, PHP compatibility, or memory issues.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Follow our guide in this case <a href=\"\/en\/help\/wordpress\/wordpress-critical-error-white-screen\/\">WordPress shows a white screen or a critical error: What to do?<\/a> continue.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">20. WordPress login does not work<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">If the public frontend is working normally, but you can no longer log in to the WordPress admin area, the website is not fundamentally offline.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Then the diagnosis should be focused on the login.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Possible causes range from password and cookie issues to security plugins and redirects.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">We specifically handle this case under <a href=\"\/en\/help\/wordpress\/wordpress-login-is-not-working\/\">WordPress login not working: Causes and solutions<\/a>.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">21. Maintenance mode after an update<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">During updates, WordPress can temporarily enter maintenance mode.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Normally, this state is automatically exited after the update is complete.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">However, if an update is interrupted, the website may become stuck in maintenance mode.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">A note like:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><code>Temporarily unavailable due to scheduled maintenance.<\/code><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">is therefore something other than a DNS, SSL or HTTP 500 error.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">In this case, check whether a WordPress, plugin, or theme update was performed immediately prior.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">22. Plugin as the cause<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">If the website crashes immediately after the installation, activation, or update of a plugin, that plugin is an obvious starting point.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">If the admin area is still accessible, the plugin in question can first be deactivated there.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">If the admin area is not accessible, a manual diagnosis via the plugin directory may be necessary, depending on the error.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">When the cause is not clear, you should investigate plugins systematically instead of deleting multiple extensions at random.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The detailed procedure follows in <a href=\"\/en\/help\/wordpress\/wordpress-plugin-theme-conflicts\/\">Identifying and Resolving Plugin or Theme Conflicts in WordPress<\/a>.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">23. Theme as a cause<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">A theme can also cause a WordPress website to no longer display correctly.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">This is especially suspicious if the error occurred immediately after:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>a theme update<\/li>\n\n\n\n<li>a theme change<\/li>\n\n\n\n<li>a change to a child theme<\/li>\n\n\n\n<li>to a change in <code>functions.php<\/code><\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">performance.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Here, too, the temporal context should be examined first.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">24. Check PHP version as cause<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">If the PHP version was changed immediately before the failure, the compatibility of WordPress, plugins, and the theme should be checked.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">For example, a newer PHP version can make deprecated code visible that previously still worked.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Conversely, a very old PHP version can be incompatible with modern WordPress software.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The PHP version should therefore not be changed up and down at random.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">How you proceed systematically with this is covered under <a href=\"\/en\/help\/wordpress\/change-wordpress-php-version\/\">Change PHP version for WordPress and check compatibility<\/a>.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">25. PHP Memory Limit<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">If PHP requires more memory during execution than allowed, a request may fail.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">A corresponding log entry can, for example, contain the text:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><code>Allowed memory size ... exhausted<\/code><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">contain.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">In this case, the cause is much more specific than the general statement \u201ewebsite unreachable\u201c.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">We discuss how WordPress and PHP memory limits are related and why increasing them is not always the actual solution at <a href=\"\/en\/help\/wordpress\/wordpress-php-memory-limit\/\">PHP Memory Limit in WordPress: Identify and fix errors<\/a>.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">26. Use error logs<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">When the server is reachable, but the processing of WordPress or PHP fails, error logs are frequently one of the most valuable sources of information.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">An error log may contain indications of, for example:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>PHP Fatal Errors<\/li>\n\n\n\n<li>Memory issues<\/li>\n\n\n\n<li>faulty plugins<\/li>\n\n\n\n<li>Theme files<\/li>\n\n\n\n<li>missing files<\/li>\n\n\n\n<li>Syntax error<\/li>\n\n\n\n<li>Problems with PHP functions<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">Pay special attention to entries whose timestamp matches the occurrence of the problem.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">27. Use WordPress debugging<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">If a WordPress or PHP problem is suspected and the available information is not sufficient, the WordPress debugging functions can help with the diagnosis.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">These include, among others:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><code>WP_DEBUG<\/code><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><code>WP_DEBUG_LOG<\/code><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><code>WP_DEBUG_DISPLAY<\/code><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">On production websites, detailed error messages should not be unnecessarily exposed to the public.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">A detailed guide will follow under <a href=\"\/en\/help\/wordpress\/wordpress-debugging-fehlerprotokolle\/\">Enable WordPress debugging and use error logs<\/a>.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">28. .htaccess as a potential source of errors<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">With certain web server configurations, WordPress uses the file:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><code>.htaccess<\/code><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">among other things for rewrite rules.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Faulty or incompatible rules can cause various problems.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The file is particularly relevant for:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>HTTP 500 errors<\/li>\n\n\n\n<li>Permalink problems<\/li>\n\n\n\n<li>Redirects<\/li>\n\n\n\n<li>certain safety rules<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">However, the file should not simply be deleted or replaced by just any version from the internet without backing up the existing configuration.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">29. WordPress core files corrupted or incomplete<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">In rare cases, WordPress core files can be missing or corrupted, for example after an interrupted update or a faulty manual file transfer.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">However, before replacing core files, it should be checked whether the error pattern actually indicates this.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Folders like:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><code>wp-content\/<\/code><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">on the other hand, your themes, plugins, and other website content and must not be thoughtlessly overwritten or deleted during a core repair.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">30. Do not change file permissions indiscriminately<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Incorrect file or directory permissions can cause access issues.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">However, it is not a good troubleshooting strategy to blanketly assign all files and directories the most permissive permissions possible.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Overly generous permissions can pose a security risk and obscure the root cause.<\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p class=\"wp-block-paragraph\"><strong>Attention:<\/strong> Never use overly broad file permissions just to \u201esomehow\u201c fix an error. Permissions should be set specifically and appropriately for the server environment.<\/p>\n<\/blockquote>\n\n\n\n<h2 class=\"wp-block-heading\">31. Might the website just be very slow?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">From a visitor's perspective, an extremely slow website can feel like an outage.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Therefore, if the page eventually appears after a long wait, you should not exclusively look for a complete server outage.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Possible causes can include, for example:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>slow PHP processing<\/li>\n\n\n\n<li>resource-intensive plugins<\/li>\n\n\n\n<li>slow database queries<\/li>\n\n\n\n<li>external services<\/li>\n\n\n\n<li>WP-Cron tasks<\/li>\n\n\n\n<li>missing or inadequate caching<\/li>\n\n\n\n<li>very large images or resources<\/li>\n\n\n\n<li>reached hosting resources<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">For this case, the separate article follows <a href=\"\/en\/help\/wordpress\/improve-wordpress-slow-loading-time\/\">WordPress is slow: Finding causes and improving loading time<\/a>.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">32. Hosting resources as a potential cause<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Among other things, a WordPress website requires CPU time, memory, PHP processes, and other server resources.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">If a website requires an extraordinary amount of resources or reaches technical limits, requests may slow down or fail.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">However, that does not automatically mean that every time a limit is reached, it should be explained by \u201einsufficient hosting.\u201c.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Unusual resource consumption can also indicate:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>faulty plugins<\/li>\n\n\n\n<li>poorly optimized processes<\/li>\n\n\n\n<li>Bots<\/li>\n\n\n\n<li>unusually many inquiries<\/li>\n\n\n\n<li>Import or backup processes<\/li>\n\n\n\n<li>hanging cron jobs<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">point out.<\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p class=\"wp-block-paragraph\"><strong>Important:<\/strong> Resource limits are a metric and not automatically the cause. The decisive factor is why the website needs the resource in question.<\/p>\n<\/blockquote>\n\n\n\n<h2 class=\"wp-block-heading\">33. Consider firewall and security mechanisms<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Firewalls and other security mechanisms can block access if requests are classified as unwanted or suspicious.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">If only a specific IP address, a specific network, or a specific action is affected, this level should also be taken into account.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Do not deactivate security mechanisms globally on a production website just to perform a test.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">34. CDN or proxy as an additional layer<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">If the domain runs via a CDN, a reverse proxy, or a comparable upstream service, there is an additional technical layer between the visitor and the actual web server.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">An error can then, for example:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>upstream service<\/li>\n\n\n\n<li>in its DNS configuration<\/li>\n\n\n\n<li>with SSL between the systems<\/li>\n\n\n\n<li>at the origin server<\/li>\n\n\n\n<li>during the connection between the proxy and the origin server<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">lie.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Therefore, the visible error page does not necessarily have to come directly from WordPress or the actual hosting server.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">35. External services can slow down WordPress<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Plugins and themes can contact external systems during a request.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">If an external API is slow or unreachable and the software being used handles this poorly, it can delay the processing of the WordPress request.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">This is another reason to investigate error logs and plugin behavior in the event of timeouts and unusually long response times.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">36. Database issues despite the website being generally accessible<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Not every database problem leads to a complete missing connection message.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Slow queries, corrupted tables, or unusually large amounts of data can also cause problems.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">However, direct changes to the database should only be made if there are concrete indications of a database problem.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">A database is not an area for indiscriminate cleanup work during an acute incident.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">37. What was changed immediately before the failure?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">As with many technical problems, the temporal context is particularly valuable.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Ask yourself:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Has WordPress been updated?<\/li>\n\n\n\n<li>Has a plugin been updated?<\/li>\n\n\n\n<li>Has a theme been updated?<\/li>\n\n\n\n<li>Has a plugin been installed or activated?<\/li>\n\n\n\n<li>Has PHP been changed?<\/li>\n\n\n\n<li>Have DNS records been changed?<\/li>\n\n\n\n<li>Has the domain been transferred?<\/li>\n\n\n\n<li>Has SSL been changed?<\/li>\n\n\n\n<li>was <code>.htaccess<\/code> Edited?<\/li>\n\n\n\n<li>Has custom PHP code been inserted?<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">An incident that begins immediately after a specific change should first be investigated in the context of that exact change.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">38. Do not change five things at once<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Systematic troubleshooting means testing hypotheses one by one.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">If you simultaneously:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Switch PHP<\/li>\n\n\n\n<li>disable plugins<\/li>\n\n\n\n<li><code>.htaccess<\/code> replaced<\/li>\n\n\n\n<li>Clear cache<\/li>\n\n\n\n<li>change DNS<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">and the website works afterwards, you may have eliminated the symptom, but you have learned hardly anything about the actual cause.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">This also makes it more difficult to prevent another failure.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">39. Do not restore backup automatically as a first step<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">A current backup is very important. Nevertheless, a complete restoration is not the best first reaction for every error.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">For example, a DNS error is not repaired by restoring a WordPress database.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">On a dynamic website, a restore can also overwrite newer content or transactions.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Therefore, try to determine first at which technical level the problem lies.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">40. Systematic diagnosis by symptom<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">For guidance, you can use the following order:<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li>Note exact error message.<\/li>\n\n\n\n<li>Test home page, subpage and admin area separately.<\/li>\n\n\n\n<li>Test another browser or another device.<\/li>\n\n\n\n<li>Use a different internet connection if needed.<\/li>\n\n\n\n<li>Check domain status.<\/li>\n\n\n\n<li>Check DNS resolution and recent DNS changes.<\/li>\n\n\n\n<li>Check SSL\/HTTPS errors.<\/li>\n\n\n\n<li>Determine HTTP status code.<\/li>\n\n\n\n<li>Investigate 404 permalinks and rewrite rules.<\/li>\n\n\n\n<li>Investigate 500 server-side errors and logs.<\/li>\n\n\n\n<li>Diagnose WordPress\/PHP on critical error.<\/li>\n\n\n\n<li>Check database connection on database error.<\/li>\n\n\n\n<li>Consider recent changes to plugins, theme, or PHP.<\/li>\n\n\n\n<li>Analyze error logs.<\/li>\n\n\n\n<li>Fix the root cause specifically.<\/li>\n\n\n\n<li>Then completely test the website.<\/li>\n<\/ol>\n\n\n\n<h2 class=\"wp-block-heading\">41. Website is back online \u2013 what now?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">When the website is working again, the diagnosis should not be terminated automatically.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Check:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Has the root cause been identified?<\/li>\n\n\n\n<li>Was the outage a one-time occurrence or repeatable?<\/li>\n\n\n\n<li>Are there still error messages in the log?<\/li>\n\n\n\n<li>Do the frontend and admin area work?<\/li>\n\n\n\n<li>Do forms and other important functions work?<\/li>\n\n\n\n<li>Must temporary changes be rolled back?<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">Especially in the case of recurring faults, it is important not just to eliminate the visible symptom.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">42. What information helps CURIAWEB support?<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">If a WordPress website is not accessible at CURIAWEB, specific technical details help narrow down the issue.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Please share if possible:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>affected domain<\/li>\n\n\n\n<li>exact error message<\/li>\n\n\n\n<li>approximate time of the first occurrence<\/li>\n\n\n\n<li>whether the problem occurs permanently or only intermittently<\/li>\n\n\n\n<li>whether the frontend and admin area are affected<\/li>\n\n\n\n<li>whether the website can be reached via another internet connection<\/li>\n\n\n\n<li>what change was made immediately before the problem<\/li>\n\n\n\n<li>whether DNS, PHP, plugins, or the theme were recently changed<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">A screenshot of the error message can also be helpful.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Do not send passwords unsolicited.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Summary<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">If a WordPress website is inaccessible, WordPress itself should not automatically be assumed to be the cause. The domain, DNS, SSL, web server, PHP, database, WordPress, plugins, and themes form different technical layers.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Therefore, start with the exact error message and then check whether the domain reaches the correct server and which HTTP or connection error is actually present.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">A 404 error requires a different diagnosis than an HTTP 500, an SSL issue, a database error, or a critical WordPress error. Changes should only be made once the faulty layer has been narrowed down.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The chronological connection to previous changes, as well as server and WordPress error logs, are particularly helpful. Systematic diagnosis prevents random changes from causing additional problems or obscuring the actual cause.<\/p>","protected":false},"excerpt":{"rendered":"<p>Wenn eine WordPress-Website pl\u00f6tzlich nicht mehr erreichbar ist, muss WordPress selbst nicht die Ursache sein. Zwischen der Eingabe einer Domain im Browser und der fertigen WordPress-Seite liegen mehrere technische Ebenen: Domain und DNS, Netzwerk, Webserver, SSL\/TLS, PHP, Datenbank und schlie\u00dflich WordPress mit seinen Plugins und Themes. Deshalb ist eine systematische Diagnose wesentlich sinnvoller als wahlloses [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"_joinchat":[],"footnotes":""},"doc_category":[80],"doc_tag":[],"class_list":["post-22419","docs","type-docs","status-publish","hentry","doc_category-wordpress"],"year_month":"2026-09","word_count":3390,"total_views":"4","reactions":{"happy":"0","normal":"0","sad":"0"},"author_info":{"name":"Silvio Mazenauer","author_nicename":"admin-curia","author_url":"https:\/\/www.curiaweb.ch\/en\/author\/admin-curia\/"},"doc_category_info":[{"term_name":"WordPress","term_url":"https:\/\/www.curiaweb.ch\/en\/hilfe-kategorie\/wordpress\/"}],"doc_tag_info":[],"knowledge_base_info":[],"knowledge_base_slug":[],"_links":{"self":[{"href":"https:\/\/www.curiaweb.ch\/en\/wp-json\/wp\/v2\/docs\/22419","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.curiaweb.ch\/en\/wp-json\/wp\/v2\/docs"}],"about":[{"href":"https:\/\/www.curiaweb.ch\/en\/wp-json\/wp\/v2\/types\/docs"}],"author":[{"embeddable":true,"href":"https:\/\/www.curiaweb.ch\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.curiaweb.ch\/en\/wp-json\/wp\/v2\/comments?post=22419"}],"version-history":[{"count":1,"href":"https:\/\/www.curiaweb.ch\/en\/wp-json\/wp\/v2\/docs\/22419\/revisions"}],"predecessor-version":[{"id":22421,"href":"https:\/\/www.curiaweb.ch\/en\/wp-json\/wp\/v2\/docs\/22419\/revisions\/22421"}],"wp:attachment":[{"href":"https:\/\/www.curiaweb.ch\/en\/wp-json\/wp\/v2\/media?parent=22419"}],"wp:term":[{"taxonomy":"doc_category","embeddable":true,"href":"https:\/\/www.curiaweb.ch\/en\/wp-json\/wp\/v2\/doc_category?post=22419"},{"taxonomy":"doc_tag","embeddable":true,"href":"https:\/\/www.curiaweb.ch\/en\/wp-json\/wp\/v2\/doc_tag?post=22419"}],"curies":[{"name":"WP","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}