Error logging - Ignoring update for disabled return channel

Flow
1

I found in the logfile the following messages. This happens 3-4x within a week. Everytime six messages are logged. There are no more information before or afterwards in the logfile. I found this question: https://github.com/vaadin/flow/issues/8562 but I’m not sure what to do know. Is this a issue / something to be worry about?

2024-03-09 09:00:42,442 WARN | https-jsse-nio-18443-exec-17 | c.vaadin.flow.server.communication.ReturnChannelHandler | Ignoring update for disabled return channel: {“type”:“channel”,“node”:1091,“channel”:0,“args”:[null]}
2024-03-09 09:00:42,442 WARN | https-jsse-nio-18443-exec-17 | c.vaadin.flow.server.communication.ReturnChannelHandler | Ignoring update for disabled return channel: {“type”:“channel”,“node”:1092,“channel”:0,“args”:[null]}
2024-03-09 09:00:42,443 WARN | https-jsse-nio-18443-exec-17 | c.vaadin.flow.server.communication.ReturnChannelHandler | Ignoring update for disabled return channel: {“type”:“channel”,“node”:1093,“channel”:0,“args”:[null]}
2024-03-09 09:00:42,443 WARN | https-jsse-nio-18443-exec-17 | c.vaadin.flow.server.communication.ReturnChannelHandler | Ignoring update for disabled return channel: {“type”:“channel”,“node”:1094,“channel”:0,“args”:[null]}
2024-03-09 09:00:42,443 WARN | https-jsse-nio-18443-exec-17 | c.vaadin.flow.server.communication.ReturnChannelHandler | Ignoring update for disabled return channel: {“type”:“channel”,“node”:1095,“channel”:0,“args”:[null]}
2024-03-09 09:00:42,443 WARN | https-jsse-nio-18443-exec-17 | c.vaadin.flow.server.communication.ReturnChannelHandler | Ignoring update for disabled return channel: {“type”:“channel”,“node”:1092,“channel”:2,“args”:[null]}

2

Close to impossible to debug if you can’t reproduce this. This can happen with frontend and server enabled state getting out of sync or for example a user is tempering with a disabled component.

3

Running our application on OpenShift produces the same. There are no user complaints that something doesn’t work.

What is the cause for those messages?

4

If I’m looking at the code correctly, the log comes from this line: flow/flow-server/src/main/java/com/vaadin/flow/server/communication/ReturnChannelHandler.java at main · vaadin/flow · GitHub

That method there is only invoked from the handle method in AbstractRpcInvocationHandler, which in turn is only invoked from handleInvocations in ServerRpcHandler.

So it looks like there needs to be a Server RPC call (client → server function call, such as a @ClientCallable method invocation from the broser) on a disabled component for that log line to appear. It could be a core component or an add-on.

5

Hi @ollit.1

That helps. Thanks for the explanation.

6

I’ve checked the project. It neither uses an addon nor has it ClientCallable anywhere.

7

You don’t need an addon for that. As an example, Grid uses @ClientCallable for the operations that delegate to the data provider.

Two additional potential sources include listening for executeJs return values and some code paths related to LitRenderer.

Finding the source might be quite tricky unless you can put a breakpoint somewhere near the line that logs the warning to see exactly what the target of the invocation is. We could potentially also improve the error message in an upcoming framework version but that’s probably not just a simple one-liner fix due to the involved indirections.