The error 'bullmq missing key for job' typically arises when BullMQ is trying to process a job, but the job key required to fetch job details from the Redis store cannot be found. This could be due to a few reasons:
Job key deletion: The most common issue is that the job key was deleted from Redis before the job could be processed or completed. This can happen if you have some other process or script cleaning up keys in your Redis instance.
Redis persistence issue: If the Redis instance where BullMQ stores its data is not configured correctly for persistence, it could be losing data on restarts or crashes.
Job created without key: In rare cases, a bug in your code may have allowed the creation of jobs without properly assigning a key.
Depending on the root cause, there are several potential solutions:
Avoid premature deletion: If you have another process or script that deletes keys from Redis, make sure it isn't deleting keys used by BullMQ prematurely. You may need to adjust this process to ignore BullMQ keys or to only delete keys when they're no longer needed.
Configure Redis persistence: Ensure your Redis instance is correctly set up for persistence. There are different methods for persisting data in Redis (RDB, AOF), and you may want to review your configuration settings.
Review job creation code: If jobs are being created without a key, look into your code where jobs are being added to the queue. Make sure each job has a unique and identifiable key attached to it.
Remember to thoroughly test changes in a development environment before deploying them to production.