Record the exact time and action that produced the failure. Check the relevant PHP or WordPress log for entries at that time, rather than diagnosing an old warning from an unrelated request.

Keep the original log privately and create a sanitised excerpt for support. Remove secrets, customer details and unnecessary account paths while preserving the error wording, component name and useful line references.

1. Identify the error class, such as an undefined function, missing class, type error or exhausted memory.
2. Look at the path to determine whether it belongs to a plugin, theme, must-use plugin or WordPress core.
3. Review the stack trace, if present, for the sequence of calls leading to the failure.
4. Compare the event with recent updates, PHP changes or custom-code deployments.
5. Reproduce the issue once on staging where practical, keeping the same relevant versions and input.

The following sanitised log is illustrative. It shows where execution stopped, but you still need the calling code and the matching request time to determine why an unexpected value reached that function.

PHP Fatal error: Uncaught TypeError:
Example\Checkout\Summary::formatTotal():
Argument #1 ($amount) must be of type float, null given
Called from wp-content/plugins/example-checkout/summary.php:42

A missing amount could originate in a caller, a changed integration response or an incomplete order state. Do not assume the named file is corrupt or fix the symptom by silently converting every invalid value to zero. Reproduce with a harmless staging order and inspect the expected input contract and error handling.

Expected result: The correction supplies valid data or handles the unsupported state deliberately. The original workflow succeeds and a missing amount produces a controlled response, without displaying private traces or creating an incorrect customer total.

An error in a plugin file after that plugin's update suggests a useful starting point, but it may still involve an incompatible dependency or unexpected input. An error in a core function can be triggered by a plugin calling it incorrectly. Avoid declaring a component malicious or defective based solely on the last path shown.

For memory exhaustion, note the limit and attempted allocation without assuming that increasing the limit is the complete solution. For missing files or functions, verify the package and dependencies before editing code manually.

Use recovery mode, a targeted plugin disable or a developer-reviewed code correction according to the evidence. Preserve the current state and a backup before replacing files. Do not remove every plugin or switch themes on a busy live site without considering forms, checkout and other dependencies.

After the correction, repeat the failing request and inspect the fresh log. Test related workflows and confirm the site is no longer displaying debug details publicly.

If the error returns intermittently, collect several timestamps and the input pattern instead of repeatedly applying the same restart or cache purge. A useful support report states what failed, which component path appeared, what changed recently and what targeted test was performed. It should not contain database credentials, private customer records or the entire configuration file.

• Using WordPress recovery mode after a plugin error
• Sharing a sanitised WordPress error log with support
• Investigating WordPress memory exhausted errors
• Resolving the editor's invalid JSON response error

• WordPress: Common Errors
• WordPress: Debug WordPress