Invalid MS-DOS Function During Restore of Encrypted Files

[Gonad]

Using SSR 2013 R2 SP4 with the latest build of Windows 10 Pro.

I have a problem restoring individual EFS encrypted files from a backup image.

After mounting the image as a virtual drive, when I try and copy an encrypted file back to its original location, I get:

Invalid MS-DOS Function Error

Same results on two different computers. I have reported this problem before (several months back) and managed to fix it by doing a repair of SSR.

It's now re-appeared on both computers but I don't know how long it's been there as this is the first time I've attempted a restore of encrypted files since the last repair.

I'm just wondering whether this could be due to critical files being changed by constant Windows 10 updates.

I'd be grateful if anyone else could try a test restore of an encrypted file and report the results back here. 

Alan

[Markus_Koestler]

Have you had filed a case for this in the past?

[criley]

I have tested this but cannot reproduce the error you are seeing.

Are there any particular file types that cause this issue?

[Gonad]

Chris,

It applies to all file types and sizes. Once again I've  performed a repair and it's now working again.

It's the second time I've experienced this particular problem simultaneously on two different computers.

That's why I was wondering whether Windows updates applied after SSR was installed is the cause of the problem.

Anyone else want to try a test?

Alan

[Gonad]

Markus,

No case has ever been opened. It was only ever reported in this forum.

Alan

[criley]

Yes, I have been able to reproduce this after running Windows Update.

However, a simple restart of the machine corrected this - I did not need to do a repair of SSR.

I am not sure if this is a Windows issue or SSR issue. Since all we are doing is a file copy from a mounted recovery point I suspect it's actually a Windows issue.

There also seems to be other, non-SSR issues out there (i.e. http://answers.microsoft.com/en-us/windows/forum/windows_10-update/windows-10-invalid-ms-dos-function/02827969-ba09-4e3f-9921-0d251d8d1758).

[Markus_Koestler]

Any updates here?

[Gonad]

Well I just tried another encrytped file restore and got the same error: Invalid MS-DOS Function Error

The computer had been powered up since a reboot about 24 hours earlier after some Microsoft updates were installed.

Tried another reboot and this time I was able to restore the files.

This is the third time now that  I've noticed this particular problem.

It's obviously there all the time but not noticed as I rarely need to restore encrypted files.