Update core database structure error 2.2.1 -> 2.3.0 [closed]

Hi,

I just updated from 2.2.1 to 2.3.0 release.
When I click the “Update core database structure” button in the Admin Center it shows me that the update was successful.
However it also displays a warning:

Warning

Update Unsuccessful [ALTER TABLE `e107_forum` ADD UNIQUE `forum_sef` (forum_sef);]

SQLSTATE[23000]: Integrity constraint violation: 1062 Duplicate entry ‘intern’ for key ‘forum_sef’

Success

Executed Update core database structure

The “Update core database structure” does not vanish, so it’s still cliackable. Usually the button should be replaced with a green tick and vanish. Is there some way I can fix this? EG change the value in the database to what e107 expects to be there, so that the updater can then update it?
 

Thanks!