test/format operation returned EINVAL:

http://build.wiredtiger.com:8080/job/wiredtiger-test-format-stress-zseries/44718/consoleFull

t: FAILED: ops/1020: (0 && ret == WT_NOTFOUND) || ret == WT_CACHE_FULL || ret == WT_PREPARE_CONFLICT || ret == WT_ROLLBACK
process aborting

This was a WT_CURSOR.modify operation in snapshot isolation, outside of a transaction, that failed, returning EINVAL.

I don't see any additional information here, so I'm going to close this ticket if it doesn't reproduce quickly.