I picked up Nifi in December and had the same issue with 502s. I couldn't find anything other than make sure your Nifi idle timeout is greater than your load balancer. Which I did. First by 1 second. Then by 10 seconds. They by doubling it. Still the same issues. I just dealt with it until today it did it to me 3 times on a complex UpdateRecord Expression Language property. AAAAhhhggg!!! During the subsequent frustratingly redundant Google result, I came across this bug for Spring Boot: https://github.com/spring-projects/spring-boot/issues/38960 I'm not Java programmer but I've heard of Spring and found that Nifi uses Spring Framework. But I didn't see Spring Boot mentioned for Nifi. So out of spite, desperation and hoping it was a similar bug, I changed my load balancer's timeout to 25 seconds. I haven't had a 502 in over 4 hours now! I was preparing to upgrade to Nifi 2.1.0 as a last ditch effort. And now I see the release notes mention updating Spring Framework. Hopefully that includes the same bug fix from January 2024 for Spring Boot. But at least now I can finish building out what I need to and worry about the upgrade when I'm done.  Hopefully this helps you (if you still need it) and it's not just a fluke or the planetary alignment. ... View more