Ok, after further testing, it works with the page size set at 300 when I selected the OU with just under 4000 users. If I change the user search base to a parent OU with much more users e.g. 50000,  it didnt seem to work no matter what page size I set. And logs not showing any errors. However it was actually still loading I think, but NiFi is not accessible during that period. What I found out is that after 30 - 35 minutes, NiFi is accessible. Not sure if its the size or something else, if I change the sync interval from 30 minutes to 10 minutes, it still took at least 30 minutes to make NiFi accessible. Taken your point, will be using the user search filter (only if they are a member of particular AD groups) to manage the expected users to be loaded in NiFi. ... View more

Thanks Matt. The user search filter is set with this value: (sAMAccountName={0}) and yes, Referral Strategy set to FOLLOW. No exceptions in the user log. When I set the base dn to a parent OU, it returns roughly 1700 users. I did try to set a page size, but when I do that, NiFi fails to start. Let me try again and set it to a smaller number, and see if works. ... View more