CIFS version 1.0 no longer mountable

[alkanen]

Windows Version

Microsoft Windows [Version 10.0.19045.5854]

WSL Version

2.5.9.0

Are you using WSL 1 or WSL 2?

• WSL 2
• WSL 1

Kernel Version

6.6.87.2-1

Distro Version

Ubuntu 22.04.4 LTS

Other Software

cifs-utils 2:6.14-1ubuntu0.3 amd64

Repro Steps

Trying to mount an old NAS with CIFS/SMB version 1.0 that worked perfectly up until a few days to a couple of weeks ago. The NAS is still mountable on my other Linux devices as well as in Windows as a network drive in the file explorer.

fstab entry:
//<nas IP>/media /mnt/nas cifs credentials=/home/<username>/.smbcredentials,iocharset=utf8,noauto,user,vers=1.0,forcegid,forceuid 0 0

Command to run:
mount /mnt/nas/

Expected Behavior

The NAS should be mounted and accessible at /mnt/nas as it has always been before

Actual Behavior

Mount command output:

mount error(22): Invalid argument
Refer to the mount.cifs(8) manual page (e.g. man mount.cifs) and kernel log messages (dmesg)

Relevant dmesg output:

[168302.564357] vers=1.0 (cifs) mount not permitted when legacy dialects disabled

[168302.564798] CIFS: VFS: vers=1.0 (cifs) mount not permitted when legacy dialects disabled

Diagnostic Logs

I can mount the Windows Network drive by running sudo mount -t drvfs Z: /mnt/nas. I can't run ls though because it gives the error "ls: reading directory 'nas': Invalid argument" but I can run cat on files that I know exist on the NAS if I mount it like this and I can navigate through sub directories as long as I know their names.

[github-actions]

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[0xbadfca11]

Same as #13031, #12987 and #12983.
https://github.com/microsoft/WSL2-Linux-Kernel/blob/linux-msft-wsl-6.1.y/arch/x86/configs/config-wsl#L3534
https://github.com/microsoft/WSL2-Linux-Kernel/blob/linux-msft-wsl-6.6.y/arch/x86/configs/config-wsl#L7173

[alkanen]

Same as #13031, #12987 and #12983. https://github.com/microsoft/WSL2-Linux-Kernel/blob/linux-msft-wsl-6.1.y/arch/x86/configs/config-wsl#L3534 https://github.com/microsoft/WSL2-Linux-Kernel/blob/linux-msft-wsl-6.6.y/arch/x86/configs/config-wsl#L7173

Ah, I would have never guessed they were related.

Does that mean I don't have to collect the WSL logs when I get back home, because the issue is already known?

[OneBlue]

@alkanen: This should be fixed in 2.6.0. Can you run: wsl --update --pre-release and see if that solves the issue ?

[alkanen]

@alkanen: This should be fixed in 2.6.0. Can you run: wsl --update --pre-release and see if that solves the issue ?

I will try to remember doing it when I get back from work tonight. Thanks for the suggestion!

[alkanen]

@alkanen: This should be fixed in 2.6.0. Can you run: wsl --update --pre-release and see if that solves the issue ?

I have tested now and the same issue remains with identical error messages. I have also rebooted my computer to make sure nothing old remained loaded.

I've also tried mounting with sudo mount -t drvfs Z: /mnt/z (where Z: is my network mount, of course) and while the mount goes through I can't list the folder contents. I can access file contents on the mounted device, but only if I know the exact path to the file in question since there's no way to use ls to navigate. Interestingly, I can do e.g. ls -l <filename> and get the file info, it's just listing directory contents that fails.

Since the update, wsl.exe --version returns:

WSL version: 2.6.0.0
Kernel version: 6.6.87.2-1
WSLg version: 1.0.66
MSRDC version: 1.2.6228
Direct3D version: 1.611.1-81528511
DXCore version: 10.0.26100.1-240331-1435.ge-release
Windows version: 10.0.19045.5965

[alkanen]

These logs are created after the upgrade:

WslLogs-2025-06-24_18-26-35.zip

[github-actions]

Diagnostic information

Detected appx version: 2.6.0.0

[OneBlue]

Thank you @alkanen. Is there a specific reason why you need to use SMB V1, which is quote old, here ? Does the mount succeed with vers=2.1 for instance ?

[alkanen]

Thank you @alkanen. Is there a specific reason why you need to use SMB V1, which is quote old, here ? Does the mount succeed with vers=2.1 for instance ?

Yes, it's an old NetGear ReadyNAS Ultra that doesn't support newer than 1.0 or I would have happily used something more recent.

Trying to mount with vers=2.1 gives this error:

mount error: Server abruptly closed the connection.
This can happen if the server does not support the SMB version you are trying to use.
The default SMB version recently changed from SMB1 to SMB2.1 and above. Try mounting with vers=1.0.
mount error(112): Host is down

I should buy something newer, but until then I'd still like to be able to access my files :)