After migrating our TFS SharePoint Portal to SharePoint 2013, our users started to complain that they couldn’t login. However when I took a look at the different site permissions, everything looked fine. All users were there as expected…
Why can’t users login?
This is caused by the new Claims based model in SharePoint 2013. In SharePoint 2010 you still had the choice between claims and the classic security model. in SharePoint 2013 this is no longer the case and therefore you have to upgrade your users to their claims alternative. As long as you don’t do this, users will not be able to access your sites.
To fix this, open the SharePoint PowerShell command line and execute the following script: