Github user mosermw commented on the issue:
https://github.com/apache/nifi/pull/2487
I tested this and I was able to switch back and forth between
MinimalLockingWriteAheadLog and SequentialAccessWriteAheadLog. +1 from me.
It's best to make this switch while there are 0 flowfiles in the
repository. With flowfiles in the system, going from MinimalLockingWAL to
SequantialAccessWAL worked, but the opposite had some issues.---
