I can't enable Azure backup on some my VMs in Azure. I have already virtual machines migrated from classic to ARM, but disks for a few one are still stored in Classic storage. If I try to enable backup I receive error "Deployment to resource group 'ResourceGroupName' failed." "Write ProtectedItems Failed" I also can't migrate this disk to ARM using standard migration procedure. On new machines or corrected migrated I can enable Azure backup without any problems.
thanks for any help