I have encountered a really odd issue with our (relativitly) new installation of SharePoint 2013, we are nearing the go-live of our intranet when we have discovered that when a standard user (read-only permissions) accesses any new sub-sites they get an access denied message.
I can give Everyone full control access to the sub-site and they will continue to receive access denied.
After many days of checking permissions and reading blogs and other questions, I have narrowed down that when the user is granted edit access to the Master Page Gallery then can access the sub-site.
I have ensured all files in the master page gallery are checked in and the couple of custom files I have developed are major versions.
Can anyone advise how I can fix this so that I don't need to give everyone edit access to the master page gallery?