BulkImport fails with a confusing message when it tries to create a temporary bulk import directory:
<path> is not in a known namespace
This is very confusing, because it refers to volumes as "namespace" (an early working term for volumes), and it does not clearly explain the constraint that bulk imported files must exist in a volume that is configured in Accumulo.
Further, as an IllegalStateException, the error message does not get propagated to the client which initiated the bulk import. Instead, an exception gets thrown indicating an error waiting for a Fate operation. One must examine the Master logs to determine the actual problem.