Intermittent 400 Bad Request – Regex Engine Timeout Error

We have been experiencing an intermittent issue for some time now, and we would appreciate your assistance in investigating it.

From time to time, our requests fail with a 400 Bad Request response and return the following error:

{

"request": {

"url": null,

"traceId": "E7A724E49B5D8B41A97C7"

},

"error": {

"code": "ApplicationResultException",

"message": "E7A724E49B5D8B41A97C7 The Regex engine has timed out while trying to match a pattern to an input string. This can occur for many reasons, including very large inputs or excessive backtracking caused by nested quantifiers, back-references and other factors.",

"date": "2026-07-14T14:57:48.8438786Z"

}

}

Could you please help us determine:

  1. What specific operation or field triggered the regex timeout?

  2. Whether there are any known limitations regarding input size or content that could cause this behavior.

  3. If there are recommended best practices to avoid this issue.

  4. Whether additional diagnostics are available using the provided trace ID.

Hello @erikrb ,

Thank you for reporting this issue.

We also received your emails regarding the same problem and have been in touch with you there. However, I'd like to post an update here as well.

The issue should now be resolved. Could you please check on your side and let us know whether everything is working as expected?

Thank you for your patience while we investigated this.

Best regards,
Aleksandra
Plumsail team