rdr_file_system 0x27 BSOD After Windows 10 2004 update, but only on domain profiles

We've been able to re-enable Offline Files.

We had this problem with 4 of 10 v2004 PCs. With one, the user could log on without BSOD'ing but it would BSOD upon browsing a network drive. The rest BSOD'd during logon until I disabled Offline Files via remote registry edit. The other 6 are getting along just fine so far.

In all 4 cases, we've worked around it by resetting Offline Files (create a FormatDatabase DWORD value set to 1 in HKLM\System\CurrentControlSet\Services\CSC\Parameters, re-enable Offline Files service and reboot the computer). Then the users can log on with Offline Files enabled.

However, the mapped drive (which maps to a DFS share, if that's relevant) is inaccessible after logon. The workaround for that has been to add a logon script that unmaps the drive, then remaps it to the non-DFS share. Initially, only the redirected folder share (also DFS) is browsable. Later, the rest of the DFS shares become browseable, perhaps after they're onlined by Offline Files.

Small sample size. Don't know how universal this workaround is, but hope it helps somebody!

Thanks for this tip, I've just managed to re-enable offline files on one of my PCs by following this. Weirdly though, File Explorer won't resolve the name of the device where the share is hosted - I can ping it by name and I can access other shares by name, but I've had to change my shortcuts to use the IP address instead.

I can read every message, but yes, problem with domain login when at home, doesn't matter connected or not (there is no domain)

Offline files is enabled, but I left it enabled.

What I noticed this far, when changing from a Office domain connected environment to a home not connected environment at startup and strangely other way around also, so maybe that is caused from wireless to wired. I've this BSOD.

I created simple local account (of course without offline files), before changing environment or after blue screen (BSOD), I login to this local account first, logout and login to domain account. Problem gone.

Now my question : Can I create something in maybe task scheduler, which does this job for me before login?

Interesting, René. 

It looks like your observation is that the problem occurs when the computer switches between offline and online mode; is that correct? So you're trying to keep it...offline? Or online?

We have same issue on serveral updated Windows 10 Pro 2004 Systems when domain user logging on with offline files activated.

A reset of the CSC cache has not helped permanently.

The following policy entry has at least fixed for us the bluescreen

rdr_file_system 0x27 BSOD

when in Airplane mode and/or not connected to any network during domainlogon in conjunction with reset of CSC Cache Folder, but reset was not on all devices needed.

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\NetCache]

"GoOfflineAction"=dword:00000000

"SlowLinkEnabled"=dword:00000001

[HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\NetCache\SlowLinkParams]

"*"="Latency=8"

The point is that the latencycheck for going offline will be here lowered down from higher standardsettings and set to 8ms (Tested with LAN and WLAN connection to Server to avoid red cross on drive for offline share connection when connection comes back) and we have tested this sucessfully with no bluescreens now since several days on affected systems

Link to Microsoft article where usage is described:

https://docs.microsoft.com/en-us/windows-server/storage/folder-redirection/enable-always-offline

@ulf_sch, no GPOs were changed.

Initially, I stopped and disabled Offline Files service on the affected computers to allow logons.

Then I experimented. I reset the Offline Files cache by setting the registry entry I described, re-enabling the Offline Files service and rebooting. Also described here as Method 2: https://support.microsoft.com/en-us/help/230738/how-to-re-initialize-the-offline-files-cache-and-database-in-windows-x. I had wondered if that would help, and another post here suggested that it did, although in a different context.

I found users could work normally, and redirected folder data was syncing to the server. However, a drive mapped (by Group Policy Preferences) to a DFS share did not work. The drive was present but couldn't be browsed. If I browsed the DFS root, I found the only DFS share present was the folder redirect share, and that only because Offline Files was on and it was offline but cached. On the affected machines, I ran a script that unmapped the drive and then remapped it to the non-DFS share to which DFS redirects:

NET USE S: /D

NET USE S: \SERVER\SHARE

I'm running the script from the Startup folder of the Start menu since it is (I hope) a temporary hack, only 4 computers were involved, and I didn't have confidence that what worked on one machine would work on all of them. I left Group Policy alone for the unaffected machines. On a large site, I'd probably use Group Policy to reset Offline Files, enable the service, and remap the drive, and then scope it to affected machines one at a time and verify it worked.

Generally speaking, the remainder of the DFS shares come back after a while, and I suspect that it's when Offline Files decides to online the shares. That seems to take a while after logon on affected machines. On non-affected machines, I don't think the shares are ever offlined.