RabbitMQ PRECONDITION_FAILED - unknown delivery tag

(Solution below)

Quoting Jan Grzegorowski from his blog:

If you are struggling with the 406 error message which is included in title of this post you may be interested in reading the whole story.

Problem

I was using amqplib for conneting NodeJS based messages processor with RabbitMQ broker. Everything seems to be working fine, but from time to time 406 (PRECONDINTION-FAILED) message shows up in the log:

"Error: Channel closed by server: 406 (PRECONDITION-FAILED) with message "PRECONDITION_FAILED - unknown delivery tag 1"

Solution <--

Keeping things simple:

• You have to ACK messages in same order as they arrive to your system
• You can't ACK messages on a different channel than that they arrive on If you break any of these rules you will face 406 (PRECONDITION-FAILED) error message.

Original answer

"PRECONDITION_FAILED - unknown delivery tag" usually happens because of double ack-ing, ack-ing on wrong channels or ack-ing messages that should not be ack-ed.

So in same case you are tying to execute basic.ack two times or basic.ack using another channel