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.
Best Answer
The reason for this is that for some reason the update has to copy files to one of those folders that is symlinked, and is unable to do so. It is looked at %systemdrive%\Users[whateverfolderhere] and is for some reason unable to move the file to where the Directory Junction is pointing.
In order to fix this problem, following these steps:
Just remember to change this if you ever change drive letters!