transactionless reported as invalid transaction mode
Under some conditions of heavy memory use, due to insufficent protectionfrom garbage collection of intermediate results within a C function, it
was possible to get an error #'transactionless' is not recognized as a
valid transactionMode. when setting the transactionMode to #transactionless.
This did not affect other transaction modes, for which the symbols are
reserved OOPs.
Workaround:
Retrying the operation should succeed.