PHP errors can make a WordPress page go blank, break the editor or prevent a contact form from working. The wording in the error log can look intimidating, but it often provides a useful starting point. The safest approach is to identify the exact error, protect your backup and change one thing at a time.

1. PHP fatal error

A fatal error stops the current request from completing. It may be triggered by incompatible plugin or theme code, a missing dependency or a programming bug. Check the log for the first fatal error and the file path involved, then test the suspected component on staging.

2. Allowed memory size exhausted

This means a PHP request reached its configured memory limit. A plugin processing a large import, a complex page or a resource-heavy task may be involved. Ask your host what the limit is and review the error log before requesting a change. Simply raising the limit may hide the underlying inefficiency rather than solve it.

3. Call to undefined function

This can happen when a required PHP extension is unavailable, a function is not available in the active environment, or a plugin expects a dependency that has not loaded. Check the exact function name, plugin requirements and hosting configuration. Do not install random PHP files to fill the gap.

4. Uncaught TypeError

Type errors occur when code receives a value of a type it cannot handle. They can appear after a PHP upgrade or plugin update exposes assumptions in older code. Update the responsible component, check its compatibility notes and report the complete error to the developer if no fix is available.

5. Headers already sent

WordPress may show “Cannot modify header information – headers already sent” when output is produced before headers or cookies are sent. The log often identifies the file and line that produced the earlier output. Check for stray whitespace, a byte-order mark or debugging output in custom PHP files; avoid editing WordPress core files.

6. Deprecated function or method notices

A deprecation notice means code is using an API that is discouraged or scheduled to change. A notice is not always the reason a site is down, but it can reveal a plugin or theme that needs maintenance. Update the relevant software and review its compatibility with the PHP version in use.

7. HTTP 500 or the WordPress critical-error screen

A 500 response is a general server error, not a PHP diagnosis. Check the PHP and web-server logs at the time of the failure. WordPress’s official common-errors documentation covers familiar symptoms and first checks.

A safe troubleshooting checklist

1. Record the exact error, time and page where it occurs.
2. Confirm that a recent file and database backup is available.
3. Check PHP, WordPress, theme and plugin versions.
4. Inspect private logs; do not display detailed errors to visitors.
5. Test suspected plugins or themes on staging when possible.
6. Apply updates from trusted sources and test the fix.
7. Recheck forms, booking tools, payments and key pages before considering the issue resolved.

Important: do not ignore PHP security updates

Compatibility troubleshooting is different from security patching. Keep the PHP runtime on a supported, patched release and work with your host if a security update exposes a compatibility issue. The official PHP release archive lists current releases and security announcements.

When should you ask for professional help?

Get help if the error repeats, you cannot access WordPress admin, the log points to custom code you do not understand, or your site handles payments or time-sensitive leads. A quick, evidence-based diagnosis is safer than repeatedly disabling plugins on a live website.

Want a second pair of eyes? Request a free five-point website review. Include the website URL, the error text and when it started. We can help identify whether the next step is a hosting check, compatibility update or wider website maintenance.