I've been searching for a few hours for information about issues with FBA after upgrading SP with no success. We are upgrading WSS 3.0 to SharePoint 2013 on a new box. The content upgrade seems to have gone fine and the Windows authentication looks OK too, but every FBA (SQL Membership) account we have tried fails with "Sorry, this site hasn't been shared with you.", though I see the user in the membership group for the site. When I delete the person and re-add them to the membership group it works, but the account string is different which I am guessing is the problem. The account value now has "i:0#.f|" added to the front.
Old string: ext|user@mycompany.com New string: i:0#.f|ext|user@mycompany.com
Is there someway to "upgrade" the FBA accounts so that everyone can log in? We can't modify them manually as there are hundreds of sites in the collection, most of which have their own permission lists.
Ok, found another command that needs to be applied and it has solved my problem.
Open SP Management Shell and execute Convert-SPWebApplication -Identity "http://your.site.url" -To Claims -RetainPermissions