Istio-proxy giving error "connection in use"

During my practice exam for Istio, in one of the questions, there were two issues. One was related to sidecar injection and another was due to connection error for istio-proxy. I was able to fix sidecar injection as hostNetwork was set to true in deployment which was causing it. But other error, I couldn’t fix. Can someone help me with it?

[2017-01-29 15:08:02 +0000] [19640] [INFO] Starting gunicorn 19.4.5
[2017-01-29 15:08:02 +0000] [19640] [ERROR] Connection in use: ('0.0.0.0', 8000)
[2017-01-29 15:08:02 +0000] [19640] [ERROR] Retrying in 1 second.
[2017-01-29 15:08:03 +0000] [19640] [ERROR] Connection in use: ('0.0.0.0', 8000)
[2017-01-29 15:08:03 +0000] [19640] [ERROR] Retrying in 1 second.
[2017-01-29 15:08:04 +0000] [19640] [ERROR] Connection in use: ('0.0.0.0', 8000)
[2017-01-29 15:08:04 +0000] [19640] [ERROR] Retrying in 1 second.
[2017-01-29 15:08:05 +0000] [19640] [ERROR] Connection in use: ('0.0.0.0', 8000)
[2017-01-29 15:08:05 +0000] [19640] [ERROR] Retrying in 1 second.
[2017-01-29 15:08:06 +0000] [19640] [ERROR] Connection in use: ('0.0.0.0', 8000)
[2017-01-29 15:08:06 +0000] [19640] [ERROR] Retrying in 1 second.
[2017-01-29 15:08:07 +0000] [19640] [ERROR] Can't connect to ('0.0.0.0', 8000)