This rather annoying message kept coming up on our on-premise (well on-Azure) SharePoint 2013 farm when we tried to create a new subsite of any kind.  After a fair amount of beating around and finding nothing around to indicate the cause, I eventually tried adding the current user to the Web Application User Policy in Central Administration and gave it Full Control.  That didn’t seem to work, still got the message.  I then tried the same again but also ticked the “Account operates as System” which did seem to work!  I then tried to add in a Security Group  with Full Control to the User Policy but this would not let me use the “Account operates as System” option.

So this workaround would appear to be OK for a test/dev/demo environment so we’ve opted for this at the moment, but seeing as you cannot have a Group operating as System it’s not really practical for production. I’ve seen other people say re-create the Web Application – well not really an option in this case.  So if anybody has the solution fit for production, please let me know!

Cheers

Dave Mc