`/proc/sys/fs/binfmt_misc/WSLInterop` does not present as boolean

[averyfreeman]

Type of issue

Code doesn't work

Feedback

Reference: https://learn.microsoft.com/en-us/windows/wsl/filesystems#disable-interoperability

Issue: disabling WSLInterop by overwriting /proc/sys/fs/binfmt_misc/WSLInterop with stdout boolean described, but not functional.

• Appears incomplete or outdated

---

User tests:

Expected:

• Response: WSL interop path return bool
• Function: Disable interoperability with Windows

echo $UID
# 0
 
echo 0 > /proc/sys/fs/binfmt_misc/WSLInterop

# sanity check:
cat /proc/sys/fs/binfmt_misc/WSLInterop
# 0

# WSL should not be able to access DrvFS:
ls -1 /mnt/c/Users/userprofile/*
# File not found

Actual:

• Response: Path returns string
• Function: Interop unaffected

# as root
echo $UID
# 0

# Documented process
echo 0 > /proc/sys/fs/binfmt_misc/WSLInterop
# bash: /proc/sys/fs/binfmt_misc/WSLInterop: cannot overwrite existing file

# sanity check:
cat /proc/sys/fs/binfmt_misc/WSLInterop
# enabled
# interpreter /init
# flags: P
# offset 0
# magic 4d5a

# WSL should not be able to access DrvFS:
ls -1 /mnt/c/Users/userprofile/*
# AppData
# Apple
# 'Application Data'
# . . . 

Also tried:

echo 0 > /proc/sys/fs/binfmt_misc/status
bash: /proc/sys/fs/binfmt_misc/status: cannot overwrite existing file

echo 0 > /proc/sys/fs/binfmt_misc/register
bash: /proc/sys/fs/binfmt_misc/register: cannot overwrite existing file

Test environment:

wsl -v
WSL version: 2.7.0.0
Kernel version: 6.6.114.1-1
WSLg version: 1.0.71
MSRDC version: 1.2.6676
Direct3D version: 1.611.1-81528511
DXCore version: 10.0.26100.1-240331-1435.ge-release
Windows version: 10.0.26200.8117

type %USERPROFILE%\.wslconfig
[wsl2]
guiApplications=true
dnsProxy=false
networkingMode=Mirrored
autoProxy=false
[experimental]
hostAddressLoopback=true

In wsl2:

cat /etc/wsl.conf
[boot]
systemd=true

[network]
generateResolvConf=false
generateHosts=false

[interop]
enabled=true
appendWindowsPath=false

[user]
default=user

[gpu]
enabled=true

uname -a
Linux localhost 6.6.114.1-microsoft-standard-WSL2 #1 SMP PREEMPT_DYNAMIC Mon Dec  1 20:46:23 UTC 2025 x86_64 GNU/Linux

cat /etc/os-release | head -n 7
PRETTY_NAME="Ubuntu Resolute Raccoon (development branch)"
NAME="Ubuntu"
VERSION_ID="26.04"
VERSION="26.04 (Resolute Raccoon)"
VERSION_CODENAME=resolute
ID=ubuntu
ID_LIKE=debian

# path folder contents:
ls -la /proc/sys/fs/binfmt_misc/
total 0
drwxr-xr-x 2 root root 0 Apr  9 20:03 .
dr-xr-xr-x 1 root root 0 Apr  9 20:03 ..
-rw-r--r-- 1 root root 0 Apr  9 20:03 WSLInterop
-rw-r--r-- 1 root root 0 Apr 10 05:48 aarch64
-rw-r--r-- 1 root root 0 Apr 10 05:48 arm
-rw-r--r-- 1 root root 0 Apr  9 20:03 llvm-21-runtime.binfmt
-rw-r--r-- 1 root root 0 Apr 10 05:48 mips64
-rw-r--r-- 1 root root 0 Apr 10 05:48 mips64le
-rw-r--r-- 1 root root 0 Apr 10 05:48 ppc64le
-rw-r--r-- 1 root root 0 Apr  9 20:03 python3.14
--w------- 1 root root 0 Apr 10 05:48 register
-rw-r--r-- 1 root root 0 Apr 10 05:48 riscv64
-rw-r--r-- 1 root root 0 Apr 10 05:48 s390x
-rw-r--r-- 1 root root 0 Apr  9 20:03 status

Page URL

https://learn.microsoft.com/en-us/windows/wsl/filesystems

Content source URL

https://github.com/MicrosoftDocs/wsl/blob/main/WSL/filesystems.md

Author

@GrantMeStrength

Document Id

4e35ecde-38e2-f0d3-1f63-0efccf02b059

Platform Id

afc96ea0-290b-b930-c2fd-bf2e8222661a