ERROR Exception occurred in REST handler: Job ***

[2020-09-15 20:06:01,677] ERROR Exception occurred in REST handler: Job 962534831b8d3dcefa22c00a992131b0 not found (org.apache.flink.runtime.rest.handler.job.JobConfigHandler)
[2020-09-15 20:06:04,666] ERROR Exception occurred in REST handler: Job 962534831b8d3dcefa22c00a992131b0 not found (org.apache.flink.runtime.rest.handler.job.JobDetailsHandler)
[2020-09-15 20:06:07,665] ERROR Exception occurred in REST handler: Job 962534831b8d3dcefa22c00a992131b0 not found (org.apache.flink.runtime.rest.handler.job.JobDetailsHandler)
[2020-09-15 20:06:10,664] ERROR Exception occurred in REST handler: Job 962534831b8d3dcefa22c00a992131b0 not found (org.apache.flink.runtime.rest.handler.job.JobDetailsHandler)
[2020-09-15 20:06:13,702] ERROR Exception occurred in REST handler: Job 962534831b8d3dcefa22c00a992131b0 not found (org.apache.flink.runtime.rest.handler.job.JobDetailsHandler)
[2020-09-15 20:06:16,669] ERROR Exception occurred in REST handler: Job 962534831b8d3dcefa22c00a992131b0 not found (org.apache.flink.runtime.rest.handler.job.JobDetailsHandler)

This is usually happening when you have a Flink UI tab open in your browser, which is left open from previous job deployments. So the UI is pointing to a URL with http://.../f9b3c58ca3026855fd2612e3c86551fa which is a JobID that doesn't exist. This causes the above log to show up.