Ok, this is the situation I had a csom low trust MVC application and wanted to change it to a high trust one.

I went through the necessary hoops and managed to get something working.

I then fired up my ‘test user’ in the high trust application and got hit with a 404 error about reading groups. Even though the groups were ‘everyone can view membership’ and my user was actually a part of some of them.

Puzzled I went to the sharepoint site with my ‘test user’ and it worked ok. Went back to my high trust site and it now worked.

There are a few queries before querying the groups for other lists, which work – it’s just these group ones that seem to cause the issue. Like I said though the issue can be resolved by the user accessing the ‘real’ site. This is however something that I would like to avoid.

Any ideas?