Macrium Full backups fail, but differential and incremental backups succeed

When a Macrium full backup runs, it fails with the following error:


Incremental and Differential backups run with no problem.

I reran the Full backup manually several times. One time it failed with a different error.


However the problem is always with the same removable USB SSD (Samsung_T5).

A user in this Dell forum thread was able to resolve the problem by "activating Bitlocker but leaving it turned off."

So I went to Control Panel -> System and Security -> BitLocker Drive Encryption:


Is Bitlocker "activated?" If I turn on BitLocker for the removable drive, won't BitLocker encrypt the drive? I really don't want to deal with passwords. What should I be doing here?

Differential and incremental backups need a base image to compare with and append to. It's not possible to have either without a Full backup.

I should have mentioned that one full backup did succeed. It was right after I migrated from Windows 10 PC to my current Windows 11 PC in early July. After three failed attempts, the last one succeeded:

But since then, no full backup succeeded. My notes do not show that I did anything special that one time- I just kept rerunning the Full backup until it succeeded. That's not a good long-term solution.

Try running a backup "outside of Windows" by booting into your MR USB recovery drive.

I may have discovered a (partial?) solution. At least it produces a different result. The Samsung_T5 USB SSD may go to sleep when it's not being used, and if so, maybe Macrium doesn't give it enough time to wake up. I unchecked "Allow the computer to turn off this device to save power."

Then I manually ran another Full backup. This time I did not get the "Volume Bitmap is Null" error, which usually occurres about 20 minutes into the backup. The backup ran for more than four hours. But since I could see no sign of progress, I killed the Macrium tasks.

After rebooting I ran another Full backup. This one ended after the usual 20 minutes, but with a different error message


Is this shadow copy a file that is supposed to be on the Samsung_T5?

Another Full backup ran to completion today. I ran it manually immediately after a Differential backup ran. I'm not saying that had anyting to do with it, but it is interesting.

I submitted a ticket to Macrium support and will let you know what I find out.