Uncaught ValueError after a PHP upgrade

Before you start

Save the complete error line and its timestamp in a private note. Record the action that failed, the current PHP versionA PHP version is a numbered edition of PHP, like 8.3. Each edition is looked after for a limited time, then gets security fixes only, then nothing. and any components updated at the same time. Share only information needed for the investigation.

Public support forums are not suitable places for customer details, access credentials or complete server paths.

Back up both files and the database before making changes. Check that the backupA backup is a separate copy of your website's files and database, so you can bring the site back after a mistake, a hack or a failed update. is usable. Work on a restricted test copy with the same PHP version and relevant settings.

Disable real payments and outgoing customer emails there. Agree who will make the change and who will check the result. These steps are an investigation guide, not a diagnosis of your particular website.

What changed? PHPPHP is a programming language that builds your web pages on the computer that hosts your site, just before they reach the visitor. WordPress runs on it. introduced ValueError in PHP 8. The manual distinguishes an incorrect value from an incorrect type: an argument can have the right type while containing an unacceptable value.

A number outside the permitted range is one example. The valid values depend on the function involved. Consult that function's manual alongside the general explanation of ValueError before deciding on a correction.

Choosing the correct repair

A concrete example is array_chunk(), which divides a collection into smaller parts. The size of each part must be at least one. Since PHP 8, a smaller size raises ValueError.

This example does not diagnose every ValueError. It explains why converting a number to another type does not necessarily help when the real problem is its permitted range.

Five steps to a repair

1. Copy the complete message into a private note. Keep the function name and argument name or position. Remove customer information before sharing the note with anyone outside the responsible maintenance team.
2. Trace the invalid value to its source. Does it come from a form, a setting or another calculation? Ask the developer to identify the first point where that value becomes incorrect.
3. Establish the valid range from the function's manual. Decide what the visitor should see for invalid input. Avoid choosing an arbitrary default without understanding what the supplied value is meant to represent.
4. Test a normal value and the boundaries of the valid range. For a positive size, zero, one and a typical larger value are useful cases. Agree the expected outcome for each case beforehand.
5. Check that the correct result is saved or displayed. Review fresh logs and repeat the test through the normal interface. A separate test script does not, by itself, cover that visitor journey.

A practical check

Imagine an administrator setting the number of items per page to zero. Agree that the form should reject it with an understandable message. Then test one item per page and a typical page size.

Include an invalid setting saved before the repair. This suggested scenario separates input validation from handling existing data. It prevents a new form from appearing fixed while a previously saved setting continues to trigger the same failure.

Getting help and checking the repair

Use the help form below if you cannot access the logs or do not know who maintains the affected code. Describe one failed action and the expected result. Ask for a proposal that separates the cause, the change and the acceptance check.

Do not include passwords with your request.

After the repair, repeat the original action on the test copy. Also check a normal visitor journey, an empty result and invalid input where relevant. Review fresh log entries at the new test time.

Keep versions and outcomes in your maintenance notes. Let the responsible administrator decide when the tested change can be applied to the live website.

Choosing the next step

Use the links below this article to choose the next step. The PHP update page helps you discuss maintenance with the administrator. The Exposure Check is a separate public check; do not treat its result as evidence that this programming error is repaired.

Use the status page for current security information. Keep the repair of the visitor action and the assessment of the server as separate checks in your notes. When requesting help, include the error text, the failed action and the expected result, but no passwords.

Ask for one responsible person to oversee both the change and its acceptance.