From what I can tell, the below error is thrown when no data for a particular table is written to a WAL, but the file is closed. This would be because the Status entry from the StatusUtil for fileClosed is pre-built and therefore does not have a createdTime. This prevents a WAL from being replicated until a createdTime entry is added manually.
From the Accumulo master:
There are two solutions I have in mind:
1. Update the StatusUtil such that every returned Status object sets the createdTime to System.currentTimeMillis if not explicitly given.
2. Update the Accumulo Master to set the createdTime to the WAL's modification time in HDFS if the WAL is closed but there is no createdTime.