Fixing WSL 2 Error 0x800701bc: Updating the Linux Kernel Component

The Error Message

You will likely encounter this error when switching a Linux distribution to version 2 or launching a fresh WSL 2 instance. Windows displays a pop-up or terminal message stating:

WSL 2 requires an update to its kernel component. For information please visit https://aka.ms/wsl2kernel
Error code: 0x800701bc

Why This Happens

WSL 1 worked by translating Linux system calls into Windows ones on the fly. WSL 2 changes this by running a dedicated, highly optimized Linux kernel inside a lightweight virtual machine. To keep the core Windows OS image smaller and allow for faster security patches, Microsoft maintains this ~16MB kernel as a separate updateable package.

Error 0x800701bc occurs when the WSL 2 subsystem is active, but the actual Linux kernel binary is missing from your C:\Windows\System32\lxss\tools folder. Without this file, Windows cannot boot the virtual environment.

Solution 1: The Manual MSI Update (Most Reliable)

If automated tools fail, downloading the installer directly is the most effective fix. This method works for both x64 and ARM64 systems.

• Download the WSL2 Linux kernel update package: wsl_update_x64.msi (approx. 16MB).
• Run the .msi file. If prompted for elevated permissions, select 'Yes' to allow the installation.
• Complete the short installation wizard.
• Open PowerShell or Command Prompt with Administrative privileges.
• Set your default version to ensure future installs use the new kernel:

wsl --set-default-version 2

Solution 2: Using the WSL Command Line

Users on Windows 11 or Windows 10 (Build 19041 and higher) can often bypass manual downloads by using the built-in update command.

• Right-click the Start button and select Terminal (Admin) or PowerShell (Admin).
• Type the following command and hit Enter:

wsl --update

Success! The terminal will show a progress bar as it fetches the latest kernel. However, if you see a list of help commands instead of an update progress bar, your current WSL version is too old to support this flag. In that case, revert to Solution 1.

Solution 3: Enable Windows Update for Microsoft Products

Sometimes your system blocks the kernel update because of restrictive Windows Update settings. By default, Windows might only look for core OS patches and ignore secondary drivers.

• Navigate to Settings > Windows Update.
• Select Advanced options.
• Find "Receive updates for other Microsoft products" and toggle it to On.
• Return to the main update screen and click Check for updates.

Verifying the Fix

After installing the package, verify the subsystem is healthy. Start by checking the overall WSL status:

wsl --status

The output should confirm you are using the latest kernel version. Next, ensure your specific distribution is actually utilizing version 2:

wsl --list --verbose

If your distribution (e.g., Ubuntu) still lists version 1 under the 'version' column, convert it manually:

wsl --set-version <distro_name> 2

Example: wsl --set-version Ubuntu 2

Maintenance Best Practices

Keep your environment stable with these three habits:

• Enable Global Updates: Keep the "other Microsoft products" toggle on so the kernel stays patched against security vulnerabilities.
• Force Restarts: If WSL becomes unresponsive after an update, run wsl --shutdown to kill the VM and restart it cleanly.
• Regular Checks: Run wsl --update once a month to benefit from performance improvements in the Linux kernel.