Problem Description

When customer who is added as Request Participants logged in to the customer portal and click on Leave this request

Upon confirming the leave request, an error is thrown:

Error
Something has gone wrong with your request. If symptoms persist contact your System Administrator.

No error is logged on the logs
Returned browser error is 400, message below:

{"errors":[{"errorMessage":"Failed to update request participants field, errors: "}],"reasonKey":"com.atlassian.servicedesk.internal.feature.reqparticipants.ParticipantUpdateFailedError","reasonCode":"400"}

Diagnostic

Check if the field configuration of the project has any custom field set as Required, and further check on the issue where the customer wants to leave has value on the custom field value.

Explanation

When attempting to leave the request, SD checks for the available field and ensure the fields pass validation. When during this state, it detects a custom field without a value where it is actually required, it fails the process silently.

This normally happen if a new custom field is introduced to the create issue page and set it to required, the old issue does not have this custom field value and it might run into this issue.

Workaround

Populate the value for the custom field on the said issue, alternatively remove the required field.