reagentc /enable failing with error code 3bc3, Windows Update failing with error 800F0922

A while back I cloned my Windows partition from my old hard drive over to a new SSD. I'm now having trouble with the latest cumulative Windows update (which is failing repeatedly with error 0x800F0922) and want to use the Windows Recovery Environment to troubleshoot.

Since I only cloned the Windows partition itself, there is currently no recovery partition, and when I tried reagentc /enable to create a new one, this fails with error code 3bc3 which translates to "The requested system device cannot be found."

What's going on and is there any way of stopping it?

This will happen if the EFI partition has the wrong GPT partition type. As it turned out, this was also causing the problem with the cumulative update.

If you are having similar issues, you can check whether this is the problem with the diskpart command. Assuming you have only one hard disk drive,

select disk 0
list partition

You should see something like this:

  Partition ###  Type              Size     Offset
  -------------  ----------------  -------  -------
  Partition 1    System             500 MB  1024 KB
  Partition 2    Primary            445 GB   501 MB

The smaller partition named "System" is the one you want, usually partition 1, so

select partition 1
detail partition

And you should see something like this

Partition 1
Type    : c12a7328-f81f-11d2-ba4b-00a0c93ec93b
Hidden  : Yes
Required: No
Attrib  : 0XC000000000000000
Offset in Bytes: 1048576

  Volume ###  Ltr  Label        Fs     Type        Size     Status     Info
  ----------  ---  -----------  -----  ----------  -------  ---------  --------
* Volume 3                      FAT32  Partition    500 MB  Healthy    System

If the file system is not FAT32 then you are not looking at the right partition. It should also be Hidden, and will not usually have a drive letter assigned unless (as in the originally posted question) it has been explicitly given one for troubleshooting purposes. It might not be exactly 500MB, but should only be taking up a small fraction of the hard disk.

The type of the EFI partition should be c12a7328-f81f-11d2-ba4b-00a0c93ec93b as shown above. If it is not, and in particular if it is ebd0a0a2-b9e5-4433-87c0-68b6b72699c7 (see Microsoft Basic Data Partition on Wikipedia) then that is likely to be the cause of the problem.

If the partition type is incorrect, you can fix this with the set id command,

set id=c12a7328-f81f-11d2-ba4b-00a0c93ec93b

The reagentc /enable command should then work, and if you are lucky, so will Windows Update.