I have a WordPress instance with the CiviCRM extension which has recently had a multi-version upgrade (it has not been managed in over 10 years). I am aware of the issues this creates as I have been working through resolving them.

The current issue I am struggling to resolve is with a Contribute page for member sign up. The page loads, the prospective member enters their details, they move to the confirmation page and then are redirected back to the original Contribute page with the only error information “DB Error: syntax error”. They have the same experience whether they select offline (invoice & pay later) or online (redirect to PayPal).

The contribution details are stored in the database (as pending/incomplete payment) as is their other address and personal information. I feel like the issue has to do with redirection to a confirmation page or payment page, but it could occur before that stage in the code.

I have rebuilt the different components of the Civi payments module (payment processors, payments methods). I have looked through the different civicrm_contribute_* tables to see if there is anything glaring. The WordPress error log, CiviCRM error log and cPanel logs are not giving any context to the error, but I can see information from the form submission request. I have tried to trace the code, this is where I am struggling with the most and probably where some direction could help me pinpoint the issue.