Fix mysqli_sql_exception after a PHP update

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.

Versions and responsibility

Ask your administrator to confirm the PHP version serving the affected website. Also record the WordPressWordPress is free software for building and editing a website in your browser. It is written in PHP, so it builds each page when someone visits., themeA WordPress theme is a ready-made package that decides how your WordPress site looks and how its pages are laid out. Change the theme and the design changes., pluginA WordPress plugin is an add-on you install in WordPress to give your site extra features, such as contact forms, SEO tools or a webshop. and bundled library versions involved. Establish which components changed during the same maintenance session.

A test using different code can give a different result even when its PHP version matches. Agree beforehand which user action will demonstrate a successful repair. Assign one responsible person to follow both the change and its acceptance check.

On the test copy, verify that scheduled jobs, payments and messages are actually separated from the live website.

Causes and PHP version

From 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. 8.1, mysqli reports errors with exceptions by default. Code that only expected a failed return value may therefore behave differently. A plugin can configure its own reporting mode, so the PHP version alone does not explain the complete behavior.

Investigate both the original database failure and the place where the application should handle it.

Choosing the correct repair

Ask the administrator to identify the failing database operation first. A missing table calls for an installation or migration review, not blindly creating a table. Connection failures require checking the intended environment.

Have the developer handle failures deliberately and ensure an unsuccessful save cannot still produce a success message or trigger inappropriate follow-up actions.

Five steps to a repair

1. Record the error code, timestamp and failed action. Remove sensitive query values from shared investigation material and keep full logs private.
2. Establish whether connection or a later database operation fails. Identify the plugin or custom module directly making the mysqli call.
3. Investigate the actual database cause on a test copy. Any schema change must follow the maintenance plan with a usable backup available.
4. Have the developer handle expected database failures appropriately. Check that a failed save cannot produce confirmation, a duplicate order or an incorrect follow-up action.
5. Repeat a successful operation and a controlled failure. Read saved records back and compare the displayed message with the actual database outcome.

A practical check

A product import module provides a useful acceptance example. Import a small agreed test file and inspect the saved products. Simulate a database failure only on the isolated test copy with developer supervision.

The import should clearly finish as unsuccessful. Repeating it should not create unwanted duplicates. This recommendation does not assume a particular cause in WooCommerceWooCommerce is a free add-on for WordPress that turns your website into a webshop, with products, a shopping cart and a checkout. or WordPress itself.

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. Use the Exposure Check to check your PHP version.

Not every server exposes its version; confirm missing information with your host. This 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.