This question already has an answer here:
I'm facing a strange problem. When I try to backup or restore any database using a SQL Server user (not sa) that belongs only to "public" server role, i have the following error when i click the browse button on the "Select backup destination" window:
Cannot access the specified path or file on the server. Verify that you have the necessary security privileges and that the path or file exists.
The user is db_owner for the database I try to backup, and SQLServer service is running with administrator account, so it should have no problems with access to the D:\SqlServerData\ folder.
I tried to add the user to any other server role, but none worked except "sysadmin". But having the user in sysadmin server role means that the user can do anything in any database, and I do not want that.
Any idea on what's going on?