Intermittent Error 500 on KoboCollect Android submissions

We are experiencing intermittent HTTP 500 errors when submitting forms via KoboCollect (Android) on our project. Submissions via the Enketo web link work perfectly with no errors.

Error message:
Error: (500) at https://kf.kobotoolbox.org/submission?deviceID=collect%3AyTTmXlqFatuiLr5E

Affected device:

  • Device ID: collect:yTTmXlqFatuiLr5E
  • KoboCollect version: v2025.3.3

Context:

  • The error occurs intermittently — some submissions from the same device succeed while others fail with 500
  • Failures occur both on submissions with and without audio attachments
  • 132 KoboCollect submissions have been successfully received; the failing ones remain on the device
  • All Enketo/web submissions (76 total) have gone through without any issue
  • The project collects data across 4 Central African countries (Cameroon, CAR, DRC, Congo-Brazzaville)
  • Data collection is currently ongoing in the field

Steps already taken:

  • Re-downloaded the form on the device
  • Redeployed the form after fixing XLSForm structural issues (begin_group/end_group formatting, instance_name formula, media column naming)
  • Tested submissions with and without audio — errors persist
  • Verified all required fields are filled before submission
  • Confirmed the server status page shows All Systems Operational

Request:
We would appreciate your help in reviewing the server-side logs for the above device ID and submission endpoint to identify the root cause of the 500 error. Given that data collection is ongoing, a prompt response would be greatly appreciated.

Please do not hesitate to contact us for any additional information.

Best regards

Welcome to the community, @yvanloic! Could you also let us know the total number of questions your form has? Please also let us know if your form has any media question types (image, audio, video, etc.) in it.