Any Azure restore from DPM fails with the error “The recovery destination selected for one or more of the files to be recovered is invalid. (ID 100070)”
This one is a bit misleading as it often makes you think the issue is with the location you have selected for the restore when in fact it indicates a problem with the Azure staging location. You must make sure it is an NTFS formatted drive with sufficient space and permissions for the agent to edit files.
In my case I saw this error when using a ReFS formatted volume. What makes this error strange is that this same drive used to be OK.
To change the location to a different drive with an NTFS file system and enough free space.
Open the DPM Administration console -> Management -> click on “online” -> Configure > Recovery Folder settings.
You will need to know the original passphrase used or be prepared to change it. You will need access into Azure to generate a new recovery vault pin to save the settings. Once the staging folder is in the right location restores should work again.