This week we hit a subtle bug that took some time to track down: command metadata was not propagating to events. Our aggregate history timeline suddenly showed events with no user attribution — just timestamps and event types.
The root cause: in Axon, commands and the events they produce have separate metadata envelopes. When you call EventAppender.append(), the new event starts with an empty metadata map.
The userId/userName we attached to commands via our AuthAwareCommandGateway stayed on the command — they never made it to the event store.
The fix was a single Spring bean:
@Bean
public CorrelationDataProvider userMetadataCorrelationDataProvider() {
return new SimpleCorrelationDataProvider("userId", "userName");
}
Axon 5’s CorrelationDataProviderAutoConfiguration picks it up automatically — no manual Configurer calls needed.
What made this especially tricky:
No errors or exceptions. Events stored fine with empty metadata. Projections updated. Everything “worked.”
Tests didn’t catch it. Unit tests for command handlers verify event payloads, not infrastructure-level metadata propagation.
The command gateway was correct. Debugging command dispatch showed metadata present. The gap only becomes visible when you inspect stored events in Axon Server.
Another lovely writedown, @petrmac. Super helpful that you’re providing input like this on the forum, so thanks a ton!
However, your predicament strikes me as a surprise. Although the configuration of interceptors and correlation data providers changed between AF4 and AF5, the nature of what data is propagated automatically from one message to another has always been the concern of the CorrelationDataProvider.
However, your pointers to me states that in AF4 this worked out of the box for you for (in this case) the userId. Perhaps a bit blunt a question, but are you absolutely certain that the previous application did not have a CorrelationDataProvider in your environment?
Alright…curious.
And, what about a custom set of interceptors that did this job?
Sorry to perhaps come across as pushy here (not my intention!). It’s just that the CorrelationDataProvider is not a new concept for Axon Framework 5. For custom correlation data like user information, we’d always have the user take on that job for themselves.
—
Now that I am typing this; are you users of the Reactor Extension in AF4? Maybe there’s something in there that did the correlation data population without consulting the user.
To be frank, I think AF should keep this as a CorrelationDataProvider concern. Hence, the work that’s currently underway to port the Reactor Extension to AF5, if anything, may have a dedicated CorrelationDataProviderfor the Reactor context.
