Did Microsoft Turn WSL into Docker? 9 Updates in the 2.9.9 Preview Reveal All

What the 2.9.9 preview actually is

WSL 2.9.9 is a pre‑release build; the stable channel is still at 2.7.12. Users who run wsl --update will receive the stable 2.7.12 version, while the preview channel provides the experimental features described below.

Core update 1: Docker‑style log timestamps

The new wslc logs command now accepts the same timestamp options that Docker users are accustomed to. The parser merges epoch seconds, Go‑style durations, plain dates, RFC3339 timestamps, and even pre‑1970 dates. Example options include: --since 1756371600 Unix epoch seconds --since 10m, --since 1h30m, --since 1.5h Go‑style durations --since 2026-08-25 Midnight of the given date --since 2026-08-25T22:00:00Z RFC3339 with timezone --since 1969-12-31 Dates before 1970

A bug that previously treated a UTC value as local time has also been fixed. Scripts that rely on the old behaviour should prefer the RFC3339 format with timezone to avoid mismatches on multi‑timezone build machines.

Core update 2: JSON volume list aligned with Docker

The wslc volume list --format json command now returns ten fields that match Docker’s output (Availability, Labels, Mountpoint, Scope, Size, Status, etc.) instead of only Name and Driver. This richer JSON is convenient for developers but can break scripts that assert an exact field set.

Parsers that ignore unknown keys continue to work; validators that require a fixed schema must be updated.

Core update 3: Container lifecycle stalls fixed

The “Container lifecycle transitions” change smooths the handling of start, stop, and state‑change boundaries, eliminating the long‑standing “WSLC stalls” issue that many users reported when running wslc run or wslc stop.

Core update 4: Network failures become visible

The “Handle Linux failures from GNS callbacks” fix surfaces previously silent guest‑side network configuration errors. When using mirrored network mode together with VPN or DNS tunnels, new error messages may appear, revealing configuration problems that existed all along.

Other minor updates

Microsoft.WSL.DeviceHost upgraded to 1.2.61 (hardware/USB stability)

Windows binaries now link a mixed CRT (no user impact)

Localization strings refreshed

Various small bug fixes

DCAT helper scripts removed (build‑artifact cleanup)

Should you upgrade? Three user personas

✅ Casual Ubuntu users

If you only run occasional Linux commands, stay on the stable 2.7.12; the preview’s new wslc features won’t affect you.

✅ Developers who already use WSL Containers

The timestamp improvements and container‑lifecycle fix are tangible upgrades. Before upgrading, back up your distro:

wsl --version                     # note current version
wsl --export Ubuntu D:\WSL-Backups\Ubuntu-before-2.9.9.tar   # backup

Then switch to the preview channel:

wsl --update --pre-release   # enter preview channel

Note: --pre-release tracks the latest preview, not a fixed 2.9.9 build.

✅ Enterprise or script‑heavy users

Because the JSON schema of volume list --format json changed and timestamps now accept more formats, perform a pilot on a few machines. Verify that your pipelines don’t rely on a fixed JSON structure, that log timestamps align across time zones, and that any network‑VPN/DNS combos don’t expose new configuration errors.

One‑sentence takeaway

WSL 2.9.9 preview shows Microsoft progressively “Docker‑izing” the wslc container command set—standardized timestamps, Docker‑compatible JSON output, lifecycle stability, and explicit network‑failure reporting—making Windows a more native platform for Linux container development.