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Federated invites from Synapse (and other servers) are rejected in v26.6.1 onwards #1971

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opened 2026-07-12 14:04:39 +00:00 by nex · 1 comment

nex commented

2026-07-12 14:04:39 +00:00

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Synapse (all versions)
Continuwuity (v26.6.0 and below)
Tuwunel (v1.7.1 and below)
Dendrite (all versions)
Conduit (v0.10.8 and below)

If someone is using one of the above servers and cannot send you an invite, you should inform them they should update their server.

Relevant Synapse pull request: https://github.com/element-hq/synapse/pull/19723

The current workaround for this is not upgrading to 26.6.1. There is an unsafe patch that makes enforcement of the new rules optional in #2072, however you forgo all security benefits by using this, and will not receive support.

Important

This is not a bug in Continuwuity - this issue is being opened for easier reference until the upstream issue is resolved.

Error messages to improve issue discoverability:

PDU in invite state (index 0) violates the room event format
PDU in invite state (index 1) violates the room event format
Invite state event is not a PDU

A year ago, Matrix introduced new validation rules for federated invites, to improve security. Versions prior to v26.6.1 did not enforce these, and also did not correctly send the new event format. As a result, invites **from** the following servers are now rejected, as they are sending malformed data (per these new rules): - Synapse (all versions) - Continuwuity (v26.6.0 and below) - Tuwunel (v1.7.1 and below) - Dendrite (all versions) - Conduit (v0.10.8 and below) If someone is using one of the above servers and cannot send you an invite, you should inform them they should update their server. Relevant Synapse pull request: https://github.com/element-hq/synapse/pull/19723 The current workaround for this is not upgrading to 26.6.1. There is an unsafe patch that makes enforcement of the new rules optional in #2072, however you forgo all security benefits by using this, and will not receive support. > [!important] > **This is not a bug in Continuwuity** - this issue is being opened for easier reference until the upstream issue is resolved. --- Error messages to improve issue discoverability: - `PDU in invite state (index 0) violates the room event format` - `PDU in invite state (index 1) violates the room event format` - `Invite state event is not a PDU`

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nex added the

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2026-07-12 14:04:39 +00:00

~~eleboucher referenced this issue 2026-07-14 17:20:27 +00:00~~

fix(pdu): Exempt m.room.create from auth_events check #1987

nex commented

2026-07-29 17:39:39 +00:00

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A temporary workaround has been pushed to an out-of-tree branch: #2072. This will not be included in the mainline software. Please please please read the big bold words that tell you how insecure it is to use this compatibility branch.

bart referenced this issue

2026-07-30 23:03:58 +00:00

Federated invite checks (JEMALLOC_SYS_WITH_LG_PAGE=16) #2078

Henry-Hiles referenced this issue

2026-08-01 19:26:44 +00:00

Federation Room invite fails "PDU in invite state (index 0) violates the room event format" for room version 10 #2084

Niklas200 referenced this issue

2026-08-01 19:35:32 +00:00

Federation Room invite fails "PDU in invite state (index 0) violates the room event format" for room version 10 #2084

Aranjedeath pinned this

2026-08-04 20:01:20 +00:00

mmaudet referenced this issue

2026-08-07 06:07:37 +00:00

fix(federation): Name the cause when invite state uses stripped events #2111

mmaudet referenced this issue

2026-08-07 10:25:19 +00:00

fix(federation): Name the cause when invite state uses stripped events #2111

nex referenced this issue

2026-08-07 21:11:48 +00:00

Federation invites always fail ("Invite state event is not a PDU") #2114

nex changed title from ~~Invites from Synapse are rejected in v26.6.1 onwards~~ to Federated invites from Synapse (and other servers) are rejected in v26.6.1 onwards

2026-08-09 14:46:51 +00:00