> Just wondering, is that a constant problem, or did it occur just on those two messages?

I don't think any new messages could be sent at that time, so I restarted WildFly today. Some messages were sent correctly a few months ago, then some time passed when I don't think any messages were sent, and then two messages were attempted to be sent in the two past days, and failed. So the WildFly server has been running for a very long time.

>Another question is, did a reboot of the WildFly server fix the problem? According to the stack, it's some problem related to the transaction execution.

I have restarted the WildFly server now, and will see if that fixes the problem.

>Would you be willing to test if the problem occurs on 1.0.3 as well?

Yes, I can do that.

Thanks,
Andreas R.