Thanks for looking onto this issue. Here's the debug info:error.log:09.04.2018 12:00:09.818 *WARN* [ForkJoinPool-1-worker-5] org.apache.jackrabbit.oak.jcr.delegate.SessionDelegate Attempted to perform hasProperty while thread ForkJoinPool-1-worker-0 was concurrently writing to this session. Blocked ...