There are five possible causes of this issue:
Cause 1: Portal account is locked.
Cause 2: Local configuration changes to firewall.
Cause 3: Changes made to CoreAD account by local IT department.
Cause 4: User has not been set up correctly.
Cause 5: There is a blank space at the end of the users Portal Username.
Resolution 1
Ask your Super User to Unlock Portal Account.
Resolution 2
Ask local IT team to revert changes made to firewall.
Resolution 3
Ask local IT team to check CoreAD user and if it was moved to a new OU on AD. Revert these changes.
Resolution 4
To resolve this issue Support will need to run some scripts on the database. Therefore please raise a new case online and reference the title of this article and please include details of the user affected.
Resolution 5
To resolve this issue Support will need to run some scripts on the database. Therefore please raise a new case online and reference the title of this article and please include details of the user affected.