After converting all of our 2010 features to SharePoint 2013, I have found that if a user with the Contribute permissions level tries to access the site, they get redirected to AccessDenied.aspx. We have given the Contribute permission level the Manage Lists permission, and this hasn't changed anything.
After noticing that 2013 uses claims based authentication by default, I created a second site using classic mode authentication, and I get the same results with both.
The complete URL that I am getting is here:
I am thinking that the URL is telling me that one of our lists is causing this problem, but the list hasn't been changed in forever, and it works great in SharePoint 2010. I believe the list was created in SharePoint 3.0's designer. I haven't found any information suggesting that old SharePoint lists won't work in SharePoint 2013.
Can anyone help me figure out what's going wrong?