No drive letter


Excuse the double posting but I just realised I should have posted here not in “News / Announcements / Feedback - CB”

I’ve just downloaded & installed Backup 3.0 on a WinXP SP3 machine. I’ve successfully done a full backup to an external USB disk of drives C: & D: plus the MBR. However, when I try to mount the 8GB ‘.cbu’ file there are no drive letters to select from in the listbox (shown at the bottom of the help page: Comodo Help). I can click the mount button and the operation appears to succeed but no additional drives show up in Windows Explorer.

Am I doing something wrong ?



Try to mount from Manage TAB, there are some issues when mounting from Restore Step 2 a partition backups that contain 2 items or more.
Also, please update to the latest version.



I’ve upgraded to the latest version of CB and tried mounting from the restore tab but still the same problem i.e. no drive letters available. The backup contains 2 drives plus the MBR.

Anything else I can try?


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With the latest version, if you click mount, no additional letters appear in Windows Explorer?


Yes that is correct, no additional letters appear in Windows Explorer.

I took a backup of the same WinXP PC but just the C: drive + MBR this time, saving to an external USB disk. I didn’t have time to try mounting it on the WinXP machine but I did try mounting it on a Win7 ultimate machine and a list of drive letters was available. The new drive letter does appear in Windows Explorer however when I try to browse it Windows asks me if I want to format the drive first! I’ve declined the offer and Windows says that the drive does not contain a recognized file system.

Any ideas ?

You can try to right click on the backup file and choose CBU Mount.
Please post screenshots of Restore Steps 2 and 3.

There is an issue with mounting from Restore Step 2. The item mounted is always the first item in “What to mount”.
The partition appears as unformatted because the first item is Track 0 and MBR and it doesn’t have a recognized file system.
You can mount from manage → Mounted drives.


Thanks for the info, that worked.

I tried mounting the original backup I made (C: + D: + MBR) on my Win7 machine via the manage tab and still I get a listbox with no drive letters. Looks like a bug then. Bit of a shame as I want to take an image of all my drives in one go. Thanks for the help though

Same problem for me ( mounting work when the CBU contain files but not partitions )

But there is a worse problem here : when trying to mount a MBR / Partitions, it corrupt my MS License database. Windows and Office are not seen as genuine anymore and only a Restore from a restore point can save me. >:(

I have the exact same issue… I was going to set this up on a server, but I created a backup of my own PC first as a test, I made an image of the entire physical disk, then mounted it.

It mounted but did not get a drive letter, and now my windows is saying its not genuine and office won’t run saying it can’t verify its license!!

If I had put this on a production server it would have corrupted the OS!

There is an issue with mounting disk backups larger than 4GB, this problem will be fixed in next release.
Most likely the backup is not corrupted, you can verify the image to be sure.


It might pay to put a warning on your homepage as it took me 4 hours to get my PC back up and running again after trailing your product.

I don’t care if it corrupted the backup image, it corrupted my PC, so I could no longer use it!

After a lot of trying to get windows and office to activate again, I had to do a repair install.

Just noticed 3.0.171317.133 has just come out, so I upgraded, but this buig is still not fixed.

Now whenever I try to mount a backup image I just get “an error occurred”

And it corrupted all microsoft licensing again, luckily this time I did it in a VM so I restored the snapshot.

Please create a debug.cbu file.