It is an internal queue that cache the data to be written to the digest log.
So your digest log is probably full.
In that case, you have two options. Either remove the digest log or use this command:
To clarify, when digest log is full, it will overwrite old data so I was not able to reproduce the “Ran out of queue space” issue.
However, I was able to reproduce the issue when using a small filesystem to hold the digest log which is explained here with solution: