Hello,
I’m trying to backup networks folders but it seems doesn’t work.
For example, first 3 links are backup but not the last one (no error):
Did I miss something ?
Thank you 
Spec: I’m using urBackup in docker format on unRAID.
Unless you’ve changed it the Urbackup service runs as a system account. It probably doesn’t have permission to access the SMB share. Change the service to run as a user that has permission to read from the paths you want to backup
Alternatively use the UNC path (\\server\share) rather than a mapped drive, SYSTEM is likely to have access that way. A drive that’s mapped for your account won’t be for the SYSTEM account UrBackup runs as. Backing up by the hidden administrative share \\SPARTA\$X\Medias… may well also work.
Alternatively there’s a registry hack which will allow SYSTEM to see the share, details HERE: https://kb.macrium.com/KnowledgebaseArticle50208.aspx