pod not found error

I am running some automated tests using RBF, but sometimes when the test runner is complete and am trying to copy the test result from OCP to local using Rsync, it shows that the pod is not found, but test cases were run on the same pod, after restarting the pod this error is resolved, but after some time again this error comes. Can anyone tell me what is the root cause of this error and the solution for this?