I have a forum in 3.0.12 and I'm migrating to 3.1.6. I have followed the steps suggested in https://www.phpbb.com/support/docs/en/3 ... /upgrade3/
In the original forum is a phpBB SEO Premod.
In the new installation (now in my localhost) I have copied the files of the phpBBSEO/usu in the ext folder and installed with the ACP. This is the only extension I have installed.
When I try to configure the "Forum URL Management" I see forum names that are highlighted in red with "A duplicate entry in title was detected for a forum ...