Microsoft has already rolled back the kernel in WSL2 while issues are debugged

What you need to know

Recently, Microsoft announced that the kernel in WSL2 would finally be bumped to a more modern version, and was pushed to a pre-release version.
The new kernel, 6.6.36.3 has now been rolled back to the much older 5.15.153.1-2 while issues are debugged.
The issues could relate to iptables, which are required for popular tool, Docker.

As an analyst with over two decades of experience in the tech industry, I’ve seen my fair share of software updates that didn’t quite go as planned. The recent rollback of the Linux kernel in WSL2 is no exception. While it’s disappointing to see a move towards a more modern version temporarily halted, Microsoft’s decision to revert back to an older kernel version while they debug the issues is a prudent one.

Microsoft recently unveiled plans to upgrade the outdated kernel employed within the Windows Subsystem for Linux (WSL) on WSL2 to a more contemporary one. However, this update has not been implemented in the stable version as of now, which is advantageous since it hasn’t been released yet.

In the latest pre-release candidate of WSL2, the kernel has been rolled back from the newer 6.6.36.3 to the previously used 5.15.153.1-2 while issues are debugged.

Here’s the full changelog for WSL2 2.3.17 which is available to download now from GitHub.

Revert Linux kernel to 5.15.153.1-2 while issues are being debugged
Fix race condition when WSL2 distribution is stopped
Use a format attribute to catch printf format errors compile time
Fix segfault in init when boot.initPath doesn’t exist
Add default Hyper-V firewall rules to allow inbound mDNS traffic
Update Windows SDK to version 26100
Update Microsoft.Windows.ImplementationLibrary to version 1.0.240803.1

In simpler terms, the update log (changelog) doesn’t explicitly mention the problems, but it might be hinting at issues related to iptables. The problem that has surfaced recently revolves around the feature, and it’s crucial to pay attention because Docker, as you may know, heavily depends on iptables.

One possible explanation from a WSL Community Telegram group I’m part of suggests that because some Linux distros are moving to nftables in place of iptables, though the kernel itself hasn’t dropped support for the latter.

As an analyst, I’d like to assure you that the current stable release of WSL2 is not being impacted at this moment. If you are already using it, everything should carry on smoothly as per usual. However, if you are on the pre-release version and have been encountering issues, I would recommend checking the GitHub page for the latest release to address those concerns.

2024-08-12 14:38

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