Summary

Users are unable to remove any request participant via REST API when the reporter is on that list.

Environment

• CLOUD 3.3.0-OD-1000.564.0
• REST API 1000.445.0
• REST API latest - https://docs.atlassian.com/jira-servicedesk/REST/cloud/#servicedeskapi

Steps to Reproduce

1. Create a ticket via REST API where the reporter is listed on the request participant's list. E.g. POST:

   https://INSTANCE.atlassian.net/rest/servicedeskapi/request
   {
       "serviceDeskId": "2",
       "requestTypeId": "16",
       "requestFieldValues": {
           "summary": "Request JSD help via REST 2",
           "description": "I need a new mouse for my Mac"
       },
       "requestParticipants": [
           "user1",
         	"MyReporter"
       ]
   }

2. Now try to remove any other participant from the list. E.g. DELETE:

   https://INSTANCE.atlassian.net/rest/servicedeskapi/latest/request/JSD-44/participant
   {
       "usernames": [
           "user1"
       ]
   }

Expected Results

• The user should be removed from the request participant's list.
  < OR >
• The error message should be clear on what the problem actually is.

Actual Results

The following error message shows up:

{
    "errorMessage": "Failed to update request participants field, errors: ",
    "i18nErrorMessage": {
        "i18nKey": "sd.request.participants.error.field.update.failed",
        "parameters": [
            ""
        ]
    }
}

Notes:

• Via UI it's possible to remove that user from the request participant's list.
• The problem only happens when the reporter is also into the request participant's list.

Workaround

Do not add the reporter into the request participant's list.