Symptoms

Upgrade fails. The following appears in the atlassian-confluence.log:

Cannot add or update a child row: a foreign key constraint fails (`confluencedb/#sql-214_69ba`, CONSTRAINT `FKBC7CE96A17D4A070` FOREIGN KEY (`PREVVER`) REFERENCES `pagetemplates` (`TEMPLATEID`))

Cause

It means there is a row in the PAGETEMPLATES table where its prevver column does not exist in the templateid column. This is a constraint violation.

Resolution

1. Roll back database to the previous state (before upgrade)

2. Search for the rogue row by running:

   select * from pagetemplates where prevver not in (select templateid from pagetemplates);
   

3. Delete it after making a backup of your database:

   delete from pagetemplates where templateid is in (select templateid from pagetemplates where prevver not in (select templateid from pagetemplates));

   
   

   If you are using MySQL, the delete command above will fail. The work around is to delete the problematic template one by one:

   delete from pagetemplates where templateid = <template_id>;

   <template_id> is the value for templateid returned from the select query.

4. Re-run the upgrade