I have noticed this crop up in a few different workbenches since upgrading to a new patched version of data interop 2021.1.2.0 (20210903 - Build 21627 - WIN64). The only solution so far is to run/cache the workbench in sections. Have tried re-installing. Plenty of storage available in the temp directory.
The fatal error occurs after saving the cache to the temp directory (but not every time):
"Saving spatial index into file..."
"Finished saving spatial index into file..."
"2022-02-15 20:43:31| 56.5| 0.1|ERROR |A fatal error has occurred. Check the logfile above for details"
It should say "Stored ### features(s) to FME feature store file...." instead of the error message.
Anyone else encountering this?