Hello Meta Box support team,
We are experiencing a recurring PHP warning on a WordPress website using Meta Box AIO and Bricks Builder:
PHP Warning: Undefined array key "_id" in wp-content/plugins/meta-box-aio/vendor/wpmetabox/mbb-parser/src/Unparsers/MetaBox.php on line 792
Between October 23 and November 3, 2026, this exact warning was logged 1,937,803 times, accounting for approximately 99.8% of all log lines. The error log grew to approximately 390 MB.
The warning is still occurring, often repeatedly within the same second. The log does not identify the triggering field group or request, and we have not yet isolated reliable reproduction steps.
Could you please advise:
1. Is this a known issue, and is a fix available?
2. How can we identify the field group or configuration that triggers the missing _id key?
3. What diagnostic information would you need to investigate this further?
We would like to resolve the underlying cause without affecting existing field definitions or stored content. We can provide a sanitized log excerpt and additional environment details.
Thank you for your help.
Best regards,
Simon
.
