What would cause W10 to loose USB memory Stick Drive assignment ?

Ztruker said:

The purpose of setting " devmgr_show_nonpresent_devices " to "1" is to show additional entries that may not show otherwise. Sometimes it does, sometimes it doesn't. I always set that environmet variable then never have worry about it again.

Thanks - I thought that was what it was for, but since I've never needed to to anything other than select view hidden dev's, and it would always show me every thing.


I may next try a in place repair maybe that will fix it ???

nikkoaki said:

Microsoft changed something about how usb storage works.. there are other bugs.. USB drives displaying weird icons (i believe in usb 3.0 ports only)

Thanks for that - I guess I'll try a in-place repair of windows to see if that works, if not I'll restore a current backup and then re-apply the CU.

Final update: After a bit of research, I realized that a "In-place update" in W10 was not going to help fix this problem.

So I mounted my M.R. Recovery USB and it was automounted with a drive letter of "L:". Which was odd, because of the other 5 different USB Sticks, never got a drive letter. I really wanted to know why this USB Stick was mounted with a drive letter (Since this is the problem). I looked at Devmgr, diskmgmt no apparent issues, So I proceeded to give it a drive letter of "F:" (Since back in June when it was created, it was mount as drive F:). I safely removed the USB Stick and remounted it. It no longer was assigned a drive letter. After some more digging I found that there was some sort of a ambiguous match error (Below). This is something I didn't look at in the beginning. All of the USB sticks were getting this error.

I decided to go ahead and restore. Choice 1 = A image just AFTER CU KB4522355 Windows 10 v1903 build 18362.449 or Choice 2 an image made just before KB4522355 was install.

I opted for the image AFTER the install of KB4522355. I did this because my system was running OK for a couple of days after the CU install.

After restoring, all USB Sticks now get their default drive letter of "F:".

I'm beginning to believe the problem was in the registry. I've had several program updates (Applications) that may have caused the problem. I will attempt to isolate this problem further if I can.

I'm going to mark this thread solved, and will update it if I find out who caused this problem.

storageman said:

I'm beginning to believe the problem was in the registry. I've had several program updates (Applications) that may have caused the problem. I will attempt to isolate this problem further if I can.

This was not the case for me, the only updates i had were KB4522355 and a .net one. Not a single thing more.
Removing KB4522355 doesn't solve the problem but doing a system restore to a day prior to when the problems started, does. Removing KB4522355 alone may not completely put the system as it was before it was installed.

I also have those messages about "devices not migrated", you can see them in device manager as well.

Yes it looks like 2 different problems.