Hello, We have also seen this issue ourselves and are actively working on it. We do not have a definite proposed solution or full RCA yet, but we have managed to narrow down the cause to stale values of relfrozenxid in the relcache for shared relations. We are in the process of coming up with a repro as well. A proposed workaround to this issue is to delete global/pg_internal.init. That will allow a vacuum of the shared relation to proceed. Thanks, Yi Wen Wong
