James 3.8, JPA Keeps Crashing // ActiveMQ Issue

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Hi Apache James Brain Trust,

I am having issues with my James server. I am running James 3.8, JPA in a
Docker Container. A user was attempting to email a large video file and
that seems to have crashed the server. I get this message in the log file:

[WARN ] o.a.a.b.r.Queue - Usage(Main:store:queue://spool:store)
percentUsage=100%, usage=20779975, limit=20765548,
percentUsageMinDelta=1%;Parent:Usage(Main:store) percentUsage=100%,
usage=20779975, limit=20765548, percentUsageMinDelta=1%: Persistent store
is Full, 100% of 20765548. Stopping producer
(ID:7a04cd6de807-43041-1775136440917-5:2:1:1) to prevent flooding
queue://spool.

I am struggling to figure out how to resolve this issue (I found this link,
but I am unable to figure where the ActiveMQ files are located) (
https://knowledge.informatica.com/s/article/Persistent-store-is-Full-100-of-Stopping-producer-ID-to-prevent-flooding-error-in-DataExchange-logs?language=en_US
).

I would appreciate your help in resolving this issue (restarting the server
has not helped). How do you stop the "producer"?

Also, where can I find the configuration file for ActiveMQ?

I would also like to know how to back up the database files, if that is
possible?

Is there any documentation on how to migrate from 3.8 to 3.9?

I look forward to any feedback.

Best regards,

Gil Espinoza

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