Fixing Error 500 in WordPress: Finding Causes and Solving Systematically

A 500 Internal Server Error is one of the more unpleasant WordPress errors because the message initially reveals very little about the actual cause. The web server received the request, but could not successfully process it due to an internal problem.

For a WordPress website, among other things, PHP errors, plugins, themes, faulty rules in .htaccess, an exhausted storage limit, or problems after a modification or update may be involved.

It is therefore important not to confuse the HTTP 500 status with the actual cause of the error.

Briefly explained: A 500 error does not automatically mean that WordPress is broken. First, check when and where the error occurs. Then, check the error logs and the changes made immediately before. Only based on this information should you [check/handle] plugins, theme, PHP, .htaccess or investigate other components in a targeted manner.

What does HTTP 500 Internal Server Error mean? #

HTTP status codes describe the result of a request between client and server.

A status code from the 5xx group indicates a server-side error. In 500 Internal Server Error the server could not complete the request as intended due to an internal error.

Thus, the report initially describes only the result – not its specific cause.

For example, the following areas can be involved in WordPress:

• PHP
• WordPress Core
• Plugins
• Themes or child themes
• .htaccess or rewrite rules
• PHP memory limit
• Files and file permissions
• Server configuration

What does a 500 error look like? #

Depending on the browser, web server, and hosting environment, the visible message may vary.

Typical designations include, for example:

500 Internal Server Error

or simply:

HTTP ERROR 500

Sometimes, instead of an explicit 500 page, a largely blank page or another generic error message appears.

Therefore, it is helpful to consider the actual HTTP status and existing server logs.

1. Check if an HTTP 500 error is actually present #

Before you modify WordPress, you should determine the error pattern as precisely as possible.

An HTTP 500 is something different than:

• 404 Not Found
• 403 Forbidden
• 502 Bad Gateway
• 503 Service Unavailable
• 504 Gateway Timeout
• DNS error
• SSL certificate error
• Error establishing a database connection

If the website cannot be reached at all fundamentally, you should first perform the broader diagnosis under WordPress website not accessible: systematically check causes use.

2. Which areas of the website are affected? #

Do not test only the home page.

For example, access the following areas:

https://deine-domain.ch

https://deine-domain.ch/eine-unterseite

https://deine-domain.ch/wp-admin

This allows the error to be narrowed down further.

Possible situations are:

• Entire website shows error 500
• only the admin area shows error 500
• only the frontend is affected
• only a single page is affected
• Error only occurs with a specific action
• Error occurs only sporadically

An error that occurs exclusively when submitting a specific form, for example, has a different starting point than a website that responds with HTTP 500 on every request.

3. What was changed immediately before the error? #

The temporal relationship is one of the most important clues when troubleshooting.

Consider whether immediately before the occurrence of the error, for example:

• WordPress has been updated
• a plugin was installed
• a plugin was activated
• a plugin was updated
• a theme has been updated
• the theme was changed
• PHP has been changed
• .htaccess has been edited
• wp-config.php has been changed
• PHP code was inserted
• a code snippet was activated

If the error started immediately after a specific change, you should start diagnosing there.

Practical Tip: During troubleshooting, try to change only one component at a time whenever possible. Otherwise, the website might suddenly start working again, but the actual cause will remain unknown.

4. Check error logs #

In the case of an HTTP 500 error, server or PHP error logs are often much more helpful than the visible browser message.

An error log may contain indications of, for example:

• PHP Fatal Error
• Syntax error
• non-existent functions or classes
• Out of memory
• Plugin files
• Theme files
• Problems with PHP extensions
• File or path issues

Above all, entries whose timestamps match the occurrence of the error are crucial.

For example, if the error was triggered at 2:32 PM, old warnings from several days prior are usually not the first starting point.

5. Evaluate file path in error log #

The file path mentioned in a PHP error message can provide an important clue.

A path like:

wp-content/plugins/sample-plugin/...

indicates that code from a plugin is involved in the error.

A path like:

wp-content/themes/beispiel-theme/...

leads in contrast toward the theme or child theme.

However, a file path is not always complete proof of the actual root cause. A component can trigger an error that only becomes visible when calling code from another component.

6. Use WordPress debugging #

When existing server logs are not sufficient, WordPress debugging features can provide additional information.

Important constants are:

WP_DEBUG

WP_DEBUG_LOG

WP_DEBUG_DISPLAY

With the appropriate configuration, WordPress can output error messages, for example, in:

wp-content/debug.log

log.

How you can use debugging in a controlled manner on a live website and read logs correctly is covered in detail at Enable WordPress debugging and use error logs.

Attention: Detailed PHP error messages should not be permanently displayed publicly on a production website. Error logs can contain internal paths and further technical information.

7. Check for a plugin as the cause of a 500 error #

Plugins are among the potential causes of an HTTP 500 error in WordPress.

A plugin is particularly suspicious if the error occurs immediately after:

• Installation
• Activation
• Update
• Modification of its configuration

begun.

If the WordPress admin area is still accessible, first deactivate the plugin in question and test the faulty request again.

If the error disappears, it should subsequently be clarified why the plugin caused the problem.

8. Disable plugin when admin area is inaccessible #

If a plugin causes the error and the WordPress admin area also no longer works, the plugin in question can be deactivated via file access if you have the appropriate experience.

Plugins are usually located under:

wp-content/plugins/

An example plugin directory could be:

wp-content/plugins/beispiel-plugin/

If this directory is temporarily renamed, WordPress will no longer be able to load the plugin under its previous path.

This method should be used selectively when the affected plugin is known or at least strongly suspected.

9. If no specific plugin is known #

If no specific plugin is known as the cause, a systematic conflict check may be necessary.

This involves systematically disabling plugins and then gradually re-enabling them until the error can be reproduced.

The goal is not simply to somehow get the website running without plugins. The crucial thing is to identify the component or combination actually involved.

You can find the detailed procedure under Identifying and Resolving Plugin or Theme Conflicts in WordPress.

10. Check theme as a cause #

The active theme can also contain PHP code that triggers an HTTP 500 error.

This is particularly relevant if the error occurs after:

• a theme update
• a theme change
• a modification of the child theme
• to a change in functions.php

occurred.

If the admin area is accessible, a suitable current WordPress default theme can be temporarily activated for diagnosis.

If the website works again as a result, the previously active theme should be examined in more detail.

11. Manually investigate topics #

If the admin area is not accessible, the theme files are usually located under:

wp-content/themes/

The directory of the active theme can be temporarily renamed for targeted diagnostics.

However, for WordPress to be able to fall back on a different theme afterwards, a suitable alternative theme must be installed.

Important: A theme change can significantly alter the appearance and certain functions of the website. In this case, it serves diagnostic purposes and should not be confused with a final design decision.

12. .htaccess as a possible cause #

On Apache-based or compatible web server configurations, WordPress can use the file:

.htaccess

for rewrite rules and further configurations.

Faulty directives or rules can cause an HTTP 500 error under certain conditions.

This can happen, for example, after:

• manual processing
• Changes made by a plugin
• Insertion of inappropriate server rules
• Migration between different server environments

occur.

13. Do not simply delete .htaccess #

If .htaccess if suspected to be the cause, you should back up the existing file first.

One possible diagnosis is to temporarily rename it, for example to:

.htaccess-backup

and then test the website again.

If the website works again afterwards, this is a strong indication that a rule in the previous file was involved.

Attention: A .htaccess- File may contain security rules, redirects or other custom configurations besides WordPress permalinks. Therefore, do not overwrite it without checking.

14. Regenerate WordPress permalink rules #

When the admin area is accessible again and a standard WordPress permalink configuration is used, the rewrite rules can be [reset/flushed] via:

Settings → Permalinks

be rewritten by saving the settings.

This is particularly relevant for permalink and rewrite issues.

If your actual error pattern concerns HTTP 404, you can find the detailed procedure under Fix 404 error in WordPress and repair permalinks.

15. Error after a PHP version change #

If the HTTP 500 error occurred immediately after changing the PHP version, the compatibility of the WordPress components should be checked.

For example, an older plugin or theme may contain PHP code that no longer works with a newer PHP version.

Conversely, modern plugins may require features that are not available with a very old PHP version.

Therefore, do not randomly switch PHP back and forth between different versions.

We cover the safe procedure under Change PHP version for WordPress and check compatibility.

16. PHP Memory Limit as the cause #

If a PHP process requires more memory than allowed, the execution can fail with a fatal error.

An error log frequently contains a message with a component such as:

Allowed memory size ... exhausted

Depending on the environment, such an error can also manifest as an HTTP 500.

However, that does not automatically mean that the memory limit should simply be set as high as possible.

High memory consumption can indicate, for example, a plugin, a complex operation, or a programming error.

We discuss the exact diagnosis under PHP Memory Limit in WordPress: Identify and fix errors.

17. Differentiate between WP_MEMORY_LIMIT and PHP memory_limit #

In the event of memory issues, it is important not to confuse various limit values with one another.

PHP has, among other things, the setting:

memory_limit

WordPress also knows constants such as:

WP_MEMORY_LIMIT

and for certain administrative processes:

WP_MAX_MEMORY_LIMIT

However, a value entered in WordPress cannot arbitrarily override a higher-level server-side limit.

Therefore, it should first be determined which limit value was actually reached.

18. Syntax error in PHP code #

A single syntax error can cause PHP to no longer execute a file correctly.

This can happen, for example, if immediately before, code in:

functions.php

wp-config.php

or another PHP file was inserted or modified.

Even a faulty code snippet can cause a fatal error.

If the error occurs immediately after a manual code change, this change should be checked first and, if necessary, reverted to the previous working state.

19. Typical PHP errors in the log #

During diagnosis, various types of PHP errors can occur.

Particularly relevant, for example, are reports such as:

PHP Fatal error

Uncaught Error

Call to undefined function

Class ... not found

Allowed memory size ... exhausted

The exact message along with the file path and line number provides significantly more information than the general HTTP 500 status.

20. Error after WordPress update #

If the error occurs immediately after a WordPress core update, you shouldn't automatically assume that WordPress itself is faulty.

An update can, for example, resolve an existing incompatibility with:

• an older plugin
• an older theme
• custom code
• an unsuitable PHP version

make visible.

Therefore, check error logs and involved components first.

21. Incomplete WordPress Update #

If an update is interrupted, files may not be completely updated under certain circumstances.

This can result in an inconsistent installation.

However, before replacing WordPress core files, you should check whether there are actually any signs of missing or damaged core files.

The distinction between WordPress Core and the following is particularly important:

wp-content/

Among other things, that is where plugins, themes, and uploads are located. This area must not be overwritten carelessly during a core repair.

22. Corrupted or missing files #

An HTTP 500 error can also occur if required PHP files are missing, corrupted, or unreadable.

Possible causes can include, for example:

• interrupted upload
• failed update
• manual deletion
• incomplete migration
• faulty restoration

In such cases, the error log often contains clues about the affected file.

23. Check file permissions – but do not change them blindly #

Inappropriate file or directory permissions can prevent the web server from correctly reading or executing required files.

However, the specific configuration depends on the hosting environment.

Attention: Do not apply wide-open permissions indiscriminately to all files or directories, such as 777, just to fix an error. This can create a significant security problem and is not a professional repair.

24. Owner and permissions are not the same #

In addition to classic file permissions, it can also be relevant at the server level which user or group owns files.

During normal WordPress management within hosting, this should not be changed manually at random.

Problems can occur, for example, after manual server migrations or file transfers with inappropriate user permissions.

25. PHP Extensions and Server Environment #

Plugins or themes may require certain PHP extensions.

If a required extension is missing, the software can respond with a comprehensible message—or crash with a PHP error, depending on how it is programmed.

The error log can then, for example, point to a non-existent function or class.

Do not install or enable PHP extensions on a hunch. First, check the requirements of the software in question.

26. Error only during a specific action #

An HTTP 500 error does not have to occur on every page load.

The error might only appear in:

• Saving a post
• Opening a specific page
• Import of large amounts of data
• Export
• Creating a backup
• Executing a specific plugin
• Submitting a form
• WooCommerce action

In this case, the concrete action is an important part of the diagnosis.

If possible, reproduce the error in a controlled manner and immediately check the corresponding log entries.

27. Error only in the WordPress admin area #

If the frontend works, but certain areas under:

/wp-admin/

generating an HTTP 500 error, it should be investigated which components are specifically running there.

For example, a plugin can load additional code exclusively during administrative actions.

An increased memory requirement of certain backend processes can also play a role.

28. Error only in frontend #

If the admin area works, but the frontend shows HTTP 500, themes, templates, frontend plugins, or specific content could be involved, among other things.

Test different pages and check whether the error occurs everywhere or only on certain page types.

29. Error on a single page only #

When almost the entire website works and only a specific URL generates an HTTP 500 error, a global server outage is rather unlikely.

Then investigate in particular:

• Page content
• used blocks
• Shortcodes
• Template
• Page Builder
• Forms
• Plugins that only become active on this page

A look into the error log immediately after accessing this URL is particularly helpful.

30. Very long processes and timeouts #

A complex PHP request can reach technical time limits.

This can be the case, for example, with:

• large imports
• Backups
• Image processing
• extensive data operations
• external API requests

occur.

Before execution times are simply increased, it should be examined why the process takes so long.

31. Properly categorizing resource limits #

Depending on the hosting environment, defined resources are available to a website.

Reaching a limit can affect requests. However, a resource limit is not automatically the actual root cause.

For example, a single faulty plugin can consume an unusually high amount of CPU or memory.

Therefore, the right question is not only:

Which limit was reached?

but also:

Why was this limit reached?

32. Cache usually does not cause a PHP fatal error #

Caching systems can cache a previously generated error page or display an outdated state after a repair.

Clearing the cache can therefore be useful after troubleshooting.

However, it does not replace the diagnosis of a server-side error.

Practical Tip: If the error log mentions a specific PHP fatal error, focus on this error first. „Clearing the cache“ is not a fix for faulty PHP code.

33. Security plugins and server rules #

Security solutions can alter server or rewrite rules, or influence access.

If an HTTP 500 error occurs immediately after a change to a security solution, this configuration should also be checked.

Do not deactivate security mechanisms globally and permanently without knowing the implications.

34. Check forwarding rules #

Faulty rules in .htaccess or other configuration levels can also cause problems.

Especially after migrations, you should check whether old rules for:

• Domains
• Directories
• HTTPS
• www or non-www
• Safety features

still fit the new environment.

35. Error after a website migration #

If HTTP 500 occurs immediately after a migration, additional causes may be considered:

• different PHP version
• different PHP configuration
• incompatible .htaccess-Rules
• missing files
• incomplete transfer
• different server modules
• incorrect file permissions

Therefore, compare the old and new environment before reinstalling WordPress.

36. Do not reinstall WordPress prematurely #

A fresh installation of WordPress is usually not the first sensible step in the event of an HTTP 500 error.

For example, if a plugin causes a syntax error, reinstalling the WordPress core will not change anything about that plugin.

Likewise, a fresh installation does not repair an unsuitable PHP version or faulty custom server rules.

Diagnosis should therefore come before reinstalling.

37. Do not restore backup automatically #

Even a full restore is not the best first action for every 500 error.

If the error log, for example, clearly names a single plugin, disabling it can be much more targeted.

On dynamic websites, a restore can also overwrite newer data.

A backup is especially valuable when:

• files have been damaged
• a change cannot be cleanly undone
• a known working state must be restored
• major changes were made to files or the database

38. Error 500 after backup restore #

If the error only occurs after a recovery, it should be checked whether:

• all files have been completely restored
• Database and files belong to the same state
• The PHP version fits
• .htaccess fits the current server environment
• File permissions are correct

A restore is only reliable if the restored state is technically consistent.

39. Check error log again after each change #

Once you have fixed a suspected cause, request the affected URL again and then check the log.

This allows you to determine:

• whether the same error occurs again
• whether a new error becomes visible
• whether the request is now successfully processed

With complex error chains, a second error may become visible after the first error has been fixed.

40. HTTP 500 and critical WordPress error #

A PHP fatal error can manifest itself both as a general HTTP 500 error and through WordPress's own error handling.

When WordPress explicitly reports that a critical error has occurred on the website, you should also consider Recovery Mode and the administrator email.

We have separate instructions for that. WordPress shows a white screen or a critical error: What to do?.

41. Systematic procedure for a WordPress 500 error #

1. Note exact error message and affected URL.
2. Check which areas of the website are affected.
3. Determine what was changed immediately before the error.
4. Check the error logs at the appropriate time.
5. Evaluate the specified file path and error type.
6. Use WordPress debugging in a controlled manner when needed.
7. Targeted check of a suspicious plugin or theme.
8. .htaccess investigate if there is any evidence.
9. Check PHP version.
10. Check the memory limit if the log shows a memory overflow.
11. Check manual code changes.
12. Examine files and permissions only in cases of concrete suspicion.
13. Fix the root cause specifically.
14. Retest affected request.
15. Check the error log again.
16. Final review of the frontend and admin area.

42. What you better shouldn't do in case of a 500 error #

• Do not reinstall WordPress immediately
• do not delete all plugins indiscriminately
• Do not change PHP, the theme, and plugins at the same time
• .htaccess do not overwrite without backup
• File permissions not generally to 777 put
• Do not arbitrarily increase the memory limit without diagnosis
• do not enable random PHP extensions
• Do not import an old database backup without checking it first
• do not display detailed error messages publicly on a permanent basis
• Do not blindly adopt server or security rules from third-party guides

43. What information helps CURIAWEB support? #

If your WordPress website at CURIAWEB shows an HTTP 500 error, as specific details as possible will help with the diagnosis.

Share in particular:

• affected domain
• affected URL
• exact error message
• approximate time of the error
• whether the error occurs permanently or sporadically
• whether the frontend and admin area are affected
• what change was made immediately before
• whether plugins, themes, or PHP have been recently updated or changed
• relevant log entry, if available

A short, relevant log excerpt with a timestamp is usually more helpful than a complete error log with thousands of older entries.

Do not send passwords unsolicited.

Summary #

A 500 Internal Server Error means that the server could not successfully process a request due to an internal error. The status code itself does not yet indicate which WordPress component is responsible for this.

In WordPress, PHP errors, plugins, themes, .htaccess, incompatible PHP versions, memory issues, and faulty files are among the possible causes.

The most important diagnostic step is therefore evaluating the appropriate error log. Error type, file path, line number, and timestamp often provide much more concrete clues than the visible 500 error page.

Then only change the component for which there is a concrete suspicion and test again after each change. A systematic diagnosis is more reliable and safer than reinstalling WordPress, deactivating all plugins, or changing server settings on suspicion.