We have updated to ELK 8.9.1, and have had a few transforms now stop with this error, "Transform "pipeline with id [blah] does not exist". The pipeline does indeed exist, and we can stop/start the transform again, after it errors.
Similarly, when indexing docs, we have had this error occur a couple of times. Again, the user does indeed exist.
"user [foo] with effective roles (assigned roles [bar] were not found)"
So. I think that, in both cases, some part of Elastic has just been unavailable for brief times, and becomes available again after it errors.
Any ideas how we can resolve, please? We had not had these problems pre 8.9.1