Home Assistant's Matter support now runs on matter.js. The Python Matter Server was archived on 23 June 2026 at version 8.1.2, and the Matter Server app 9.0 replaces it as a drop-in that migrates its data automatically on first start. Take a full backup before updating: the announcement describes no downgrade path.
- 8.1.2 is the last Python release. The repository is archived and receives no updates or support.
- App 9.0 migrates on first start. No manual export, but no documented way back either.
- Back up before updating, and keep that backup until every Matter device has reported in.
- IPv6 still decides everything. The new server changes nothing about the network Matter needs.
What actually changed
Home Assistant does not talk to Matter devices itself. A separate process, the Matter Server, holds the controller and the fabric, and the Matter integration connects to it. Until 2026 that process was python-matter-server, built on the official C++ Matter SDK.
Its README now opens with a notice: the server “was rewritten and moved to matterjs-server”, version 8.1.2 “is the final version of the python-matter-server, libraries, and docker-container”, and users should migrate “as soon as possible”. The repository was archived on 23 June 2026, the same day Home Assistant announced Matter Server app 9.0.
| Before | Now | |
|---|---|---|
| Project | python-matter-server | matterjs-server |
| Built on | Official C++ Matter SDK | matter.js (TypeScript) |
| Licence | Apache-2.0 | Apache-2.0 |
| Version | 8.1.2, the final release | Matter Server app 9.0 (23 June 2026) |
| Status | Archived, no support | Maintained |
Your devices, the fabric and multi-admin sharing with Apple, Google or Amazon are Matter features, not features of the server. The rewrite replaces the controller software; it does not change the protocol your devices speak.
Before you press update
The announcement describes app 9.0 as a “fully compatible drop-in replacement” that will “automatically migrate your data on the first start”. That is convenient and it is also the reason to prepare: the migration happens once, without asking, and the post describes no route back to 8.1.2.
- Take a full backup that includes the Matter Server app, not only Home Assistant's configuration. In the announcement thread, at least one user reverted by restoring exactly that.
- Write down which devices are Matter. After the update you will want to confirm each one reports in, and the list is quicker to check than the device page.
- Check IPv6 on the host. The integration documentation asks for IPv6 set to Automatic or static under Settings, System, Network, and for IPv6 multicast to reach the host freely. A network that was marginal before will stay marginal after.
- Update during a quiet hour, not before you leave the house for a week.
What users report afterwards
These come from replies in the official announcement thread, not from our own testing. They are worth knowing because each has a simple first check.
| Report | First thing to check |
|---|---|
| Some Matter devices show as unavailable | Give battery and Thread devices time to report in, then confirm the Thread border router is online |
| Power and energy entities missing on some smart plugs | Whether a later 9.0.x release mentions the device; the thread already mentions 9.0.1 and 9.0.2 |
| Higher CPU use, quoted at 17 to 20 % on a Home Assistant Green against 3 to 5 % before | Whether it settles after the first hours of migration and discovery |
| Some device types missing from the network visualisation | Cosmetic: control is unaffected if the entities work |
The thread already mentions 9.0.1 and 9.0.2 after 9.0. When a device misbehaves after a big rewrite, the cheapest fix is often the next patch release, so update the app again before reaching for a reset.
If you run the server in your own container
People on Home Assistant Container or Core often ran the python-matter-server Docker image themselves. That image will not be updated again. The replacement, matterjs-server, is published separately under the same Apache-2.0 licence and needs Node.js 22.13 or later (24 is the version its README recommends) if you run it outside a container.
Its README describes migration from the Python storage format as supported, aims for API compatibility with the old server, and points Home Assistant users to the official app rather than a hand-rolled install. If you do not have a specific reason to self-host the controller, the app is the path the maintainers support.
Nothing in the rewrite removes that requirement. The Home Assistant documentation is explicit that a Thread-based Matter device needs a border router nearby and Thread credentials synced to the phone you commission from. Our Thread guide covers the failures that follow when either is missing.
Sources
- python-matter-server repository and archive notice
- matterjs-server repository and README
- Home Assistant announcement: Matter Server app 9.0 (23 June 2026) and replies
- Home Assistant Matter integration documentation
Checked on 7 October 2026. Version numbers and repository status come from the GitHub API on that date.
Frequently asked
Do I have to re-pair my Matter devices?
No. The announcement says app 9.0 migrates the existing data automatically on first start, so the fabric and its devices carry over.
Can I go back to the Python server?
The announcement describes no downgrade path. Restoring a full backup taken before the update is the reliable way back.
Is the new server open source?
Yes. matterjs-server is published under Apache-2.0, the same licence as the Python server it replaces.
Does this change anything for Thread devices?
Not the requirements: a nearby Thread border router and synced Thread credentials are still needed to commission them.
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