How to Fix an Unreal RepNotify (OnRep) Not Being Called

An OnRep not being called is a replication setup or no-change issue. Here is how to fix it.

How to fix it

1. Mark the property ReplicatedUsing

The property must be declared with ReplicatedUsing pointing at the OnRep function, and registered in GetLifetimeReplicatedProps. Without this, the value does not replicate and OnRep never fires.

2. Change the value on the server

OnRep fires on clients when the replicated value changes. Change the property on the server (the authority); changing it on a client does not replicate and does not trigger OnRep on others.

3. Ensure a real change and replication

OnRep fires only when the value actually changes from what the client had. Setting it to the same value does not trigger it. Also confirm the actor replicates, or no properties replicate at all.

Catching the ones you can't reproduce

The hardest version of this to fix is the one you can't reproduce — it only happens on a player's hardware, OS, driver, or save state, under conditions that simply aren't present on your machine. A report that says “it crashed” or “it froze” gives you nothing to act on, so the bug survives release after release while quietly costing you players.

Automatic error capture closes that gap. Each failure arrives with its full stack trace, the device and OS, the build number, and a breadcrumb trail of what the player did right before it broke, so even a failure you have never seen becomes a specific, reproducible issue. Fold identical failures into one signature ranked by how many players each hits, and your worklist sorts itself worst-first instead of arriving as a stream of vague complaints.

This is where a tool like Bugnet earns its place. Its SDK captures every Unreal Engine error automatically with the full stack trace plus device, OS, memory, build, and game-state context, folds duplicates into one grouped issue with an occurrence count, and ties each to the build it first appeared on — so you fix the problem that hurts the most players first and confirm it is gone when its signature disappears from the next release.