@Pratyush1  The more detail you can provide, the better here. In addition to what @cassie2698bratt suggested: Apache NiFi 1.14 was released 3 years ago and has had many important bug fixed, security fixes, and improvements since then,  The latest 1.x release is Apache NiFi 1.26 as of writing this response.  I strongly recommend upgrading to the latest release. What Java vendor and version are you using with your NiFi.  NIFi supports Java 8 (and 11 in newer releases).  Java 8 update 252 or newer is required minimum.  All nodes consistently on same version? What OS is being used on server where NiFi is having issue? Is this a NiFi multi-node cluster?  Does UI of every node in same cluster present same issue while loading the UI or is it specific to just one node in the cluster? Any custom code add-ons? Are the other systems using the same Java and NiFi versions? Any observations in the NiFi logs when accessing the UI? Thank you, Matt ... View more