Servers don't enforce PDU format

[Kladki]

In the room version specification, it states the format for PDUs. However, all the requirements are not fully enforced.
For example, you can send an m.room.canonical_alias event with content of null to a room, and despite that content must be an object in room version 10, Synapse, Dendrite, and Conduit allow for that event to be appended to the timeline, one way or another.

I have not tested whether all of requirements are enforced, but I would assume there is no explicit validation of the PDU format, with the only checks being side effects of things like authorization checks being performed.

[richvdh]

In the room version specification, it states the format for PDUs. However, all the requirements are not fully enforced.

That sounds more like an implementation issue than a spec issue?

[Kladki]

I think it is similar to #1506 in the sense that while it is an implementation issue, the fact that no known implementation actually enforced this would make this be de-facto behavior.