This was working well on 2.6.x
Upgraded to 2.7.1 Stable and get this error immediately when trying to use this option (flag → delete spammer) on a post or topic:
There was an error deleting that user. Make sure all posts are deleted before trying to delete the user.
‘delete user max post age’ and ‘delete all posts max’ are both set to the max value of 2000000000.
This option used to delete all of the user’s posts and the account itself.