This is odd to me, but I think someone will recognize the cause immediately.
Backblaze said it could not backup a volume because it was expecting the volume to be named “SD Mac-16 on Wabbit 3” but the volume is now named “SD Mac-16 on Wabbit 3.” But I thought the volume is named “SD Mac-16 on Wabbit”!:
Looks like a volume (in this case a disk image) has two names: The name I can see in the finder and apparently, a name the system knows, perhaps to resolve naming conflicts? Look at the Get Info box:
The system adds the “3” and I guess it used to be “2.” Backblaze was used to seeing it as 2 and now, even though it seems to know it’s the same volume, it now sees 3 and refuses to do the backup.
I changed that “Name & Extension” field but the system soon changes it back.
I ran into this issue too! Originally I believed it was because my apartment looks on to a train track and the vibrations from them coming by were loosening the connection to my laptop.
I bought shock absorbing mats and spread them across my desk. Still didn’t work
I ended up swapping the cable I received with the drive for a thunderbolt cable from Apple and haven’t bumped into this issue since!