Problem

When attempting to assign a work item to an active user that has a conflict with a former user record, it errors out stating that "We couldn't update the assignee value"

This also seems to impact comments, work item history and work item activity.

Prerequisites

The issue occurs when the active user has a backend username (not display name) data value conflict with a former user record.

Steps to Reproduce

1. Find a scenario of the conflict described above
2. Try to assign a work item to a user with conflict

Expected Results

User should be assigned to the work item successfully and conflict should not exist.

Actual Results

User can't be assigned to the work item regardless of how it is done.

Workaround

Contact support and ask them to identify and resolve active user in conflict with former users data, explaining about the symptoms observed.