Quick answer: Unreal Iris clients disconnecting after a server hot-patch bumped an actor archetype version? Versioned archetypes are compatibility checks - distribute the patch to clients or revert.
Server patch added a replicated property. All clients dropped with archetype mismatch.
Patch clients in lockstep
Plan server patches alongside client patches. Iris archetypes are versioned; both sides must agree.
Use forward-compatible properties
Add new properties marked NotReplicated initially; flip to replicated once clients have the version. Two-step deploy.
Or roll back
If clients can't be patched immediately, roll the server back. Iris compatibility is strict; mismatch is fatal.
“Iris is type-safe across the network. Type safety extends to versions.”
If you run live multiplayer, archetype versioning belongs in your deployment runbook. Document the rollout sequence.