When using a share folder of windows server 2012 R2 storage destination, Backup Exec is unable to create the disk storage.
1. everything working fine at BE V16, issue happened after upgrade to BE V20
2. tested domain / local admin account both shown below BE error message, but both account can access storage destination folder from BE server
Unable to create the disk storage, error shown as below
I can simulate the error message you encountered in my backup exec server.
I tried to grant my Backup Exec service with read only permission in share folder, then I got the error message in your post.
I read your post again. Seem you have changed the error message. From your latest error, obviously relate to permission,.
Please try to grant everyone with full control in share permission.