You (or your used software) appear to be using appends on files that are being modified in parallel by other concurrent jobs/workflows/etc.. HDFS uses a single-writer model for its files, so observing this error is normal if your software does not have logic handling it and waiting for a proper writer lease to perform its work. Without audit logs of the filenames involved, there's little more we can tell. We also advise against using appends unless you absolutely require it for your use-cases. ... View more