Today I’ll talk about a problem that I recently met.
After an audit, it was found that a site collection was reachable by anonymous users.
Some site collections are accessible to anonymous but this one should not, so my first think was to go set anonymous permissions at the site collection level.
However when I tried to confirm the change, I was surprised to see a message “access denied”. For precision, I use an account that is part of the “Site Collection Administrators”
A little confused, I tried using a PowerShell command and the same error happens.
After more research, I finally thought of something. This site collection is not actively used, it is used for old documents storage. Perhaps the former consultant had set it read-only!
To check this, I went in the central administration see the status of “lock”
Hope this helps.