What happened?
Starting from spec version 1.16, the Matrix protocol has required a new format for federated invites as a security measure. Servers who do not use this new format will have their invites rejected by conforming ones.
Although the Continuwuity homeserver started enforcing the new validation rules since mid-July 2026, Synapse had been notoriously slow to roll out their side of the change. This resulted in many months where federated invites from Synapse to Continuwuity were broken, which only ended with the release of Synapse v1.162.0. For 79 days, the core functionality were unusable for users across the two most deployed homeserver implementation of the public ecosystem.
While invites finally function now, this website persists to track the plenty of tasks left to be done. Other servers in the ecosystem still need to fix their invite mechanism, in terms of both sending correctly formatted invites and validating received ones. Those who do not update are more vulnerable to various security issues, and will eventually fail to send invites at all as the ecosystem upgrades.
Servers compliance list
| Send valid invites | Enforce invite validation | |
|---|---|---|
| Continuwuity | ✅ - since v26.6.1 | ✅ - since v26.6.1 |
| Zendrite | ✅ - since v3.4.0 | ✅ - since v3.4.0 |
| Synapse | ✅ - since 1.162.0 | ❌ - ETA 2027-06-01 |
| Conduit | ✅ - since v0.10.9 | ❌ |
| Tuwunel | ✅ - since v1.8.0 | ❌ |
| Dendrite | ❌ | ❌ |
| Venator | ❌ - in absentia | ❌ - in absentia |
What can I do about this?
If you are a homeserver operator, wait for your homeserver software implementation to fix their invites and upgrade accordingly. You can also urge other homeserver operators you know to upgrade as well.
If you are operating a homeserver that validates invites correctly, DO NOT downgrade your server to a non-validating version, as this may introduce grave security risks.
If you are a user of a non-conforming homeserver and wish to invite others, you may:
Urge your homeserver admin to upgrade their software
Send invites only from a homeserver that conforms to MSC4311 (see table above)
Make an invite-only room public for a brief moment for the intended invitee to join, then make the room invite-only again
When starting DMs, ask the user of the conforming user to create the room and invite you instead
Spread the word about this issue
Related links
MSC4311: Ensuring the create event is available on invites - The MSC resulting in the new invite format
Synapse PR to fix broken invites: element-hq/synapse#19723
Synapse release with fixed invite: v1.162.0
continuwuation/continuwuity#1971 - Continuwuity's issue tracking federated invite failure
View the timeline of events.
Our 88x31:
Our last 88x31 before Synapse fixed itself (was updated every day)
This website is open source