Error 160 was seen after switching a transaction-controlled index into non-transaction mode. The error was caused by transaction-mark cleanup optimization skipping the clean-up of some marks. The logic has been modified to correct this.
Workaround: Add the following options to ctsrvr.cfg and restart FairCom Server:
COMPATIBILITY NO_MYMARKS
COMPATIBILITY NO_NXTMARKS
COMPATIBILITY NO_UPDMARKS
Note that these configuration options will only prevent future occurrences of the error. Any indexes already experiencing errors will need to be rebuilt.