422 Unprocessable Entity: Queue or Topic spool limit exceeded

[mig1]

I'm seeing this error when publishing messages using the REST API. What's the reason and what can I do to fix it?

My resource allocation looks fine in my opinion.

[mig1]

It's almost been 24 hours and my client is still blocked. I tried to change the resource units for it, from 10 to 50. No difference.

I can still publish to other clients in the sub account.

[mig1 · Accepted solution]

I'll answer this myself.

When a queue has reached its maximum size, subscribed to the topic at hand, it's no longer possible to post to that topic. The maximum size of a queue is roughly 1.5 GB and can't be configured higher.

This causes some weird scenarios where a client that for whatever reason isn't processing incoming messages actually blocks broadcasting of new messages.

[Srinivas-Rao · Accepted solution]

Hi mikael.gurenius4 - Thanks. It is definitely insightful but 1.5GB is too much of memory considering that most of the event payloads are too small in size ( generally having the business object ID in the payload ). So, yes - I can see this happening only in some weird scenarios where the message consumption by recipients is blocked...

[mig1 · Accepted solution]

True, they are usually small. In my case, I was pushing a full load from the ECC Event Enablement Add-On, containing quite a few business objects from Plant Maintenance with a few additional fields (not just the ID). The 1.5 GB limit was quickly reached.