When upgrading from Exalate 3. X version to 4. X the following error is raised:
We are using Atlassian Active Objects framework to interact with the MS SQL database. A problem with a unique constraint on one of our database tables during the upgrade causes the error.
U_AO_08F1AF_INSTANCE_NAME is a stale object, which relates to Exalate but is created by the Active Objects framework of the Jira on-premise instance. It fails to be cleaned up in the course of the upgrade.
Drop the index U_AO_08F1AF_INSTANCE_NAME manually and re-install the Exalate app.