Here is an example of some of the error messages we are seeing depending on the connect box within the distributed cluster:
[2019-07-17 19:21:58,408] ERROR Failed to reconfigure connector's tasks, retrying after backoff: (org.apache.kafka.connect.runtime.distributed.DistributedHerder) │
│ org.apache.kafka.connect.runtime.rest.errors.ConnectRestException: IO Error trying to forward REST request: org.eclipse.jetty.client.HttpResponseException: HTTP protocol violation: Authentication challenge │
│ without WWW-Authenticate header │
│ at org.apache.kafka.connect.runtime.rest.RestClient.httpRequest(RestClient.java:108) │
│ at org.apache.kafka.connect.runtime.distributed.DistributedHerder$18.run(DistributedHerder.java:1034) │
│ at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) │
│ at java.util.concurrent.FutureTask.run(FutureTask.java:266) │
│ at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) │
│ at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) │
│ at java.lang.Thread.run(Thread.java:748) │
│ Caused by: java.util.concurrent.ExecutionException: org.eclipse.jetty.client.HttpResponseException: HTTP protocol violation: Authentication challenge without WWW-Authenticate header │
│ at org.eclipse.jetty.client.util.FutureResponseListener.getResult(FutureResponseListener.java:118) │
│ at org.eclipse.jetty.client.util.FutureResponseListener.get(FutureResponseListener.java:101) │
│ at org.eclipse.jetty.client.HttpRequest.send(HttpRequest.java:683) │
│ at org.apache.kafka.connect.runtime.rest.RestClient.httpRequest(RestClient.java:89)
│
│ [2019-07-17 19:24:16,048] DEBUG Found protocol handler org.eclipse.jetty.client.WWWAuthenticationProtocolHandler@af86f8e (org.eclipse.jetty.client.HttpReceiver) │
│ [2019-07-17 19:24:16,048] DEBUG Response begin HttpResponse[HTTP/1.1 401 Unauthorized]@ec7ea09 (org.eclipse.jetty.client.HttpReceiver) │
│ [2019-07-17 19:24:16,048] DEBUG HEADER:Date --> VALUE (org.eclipse.jetty.http.HttpParser) │
│ [2019-07-17 19:24:16,048] DEBUG HEADER:Date --> IN_VALUE (org.eclipse.jetty.http.HttpParser) │
│ [2019-07-17 19:24:16,048] DEBUG HEADER:Date --> FIELD (org.eclipse.jetty.http.HttpParser) │
│ [2019-07-17 19:24:16,048] DEBUG HEADER:Content-Type: application/json --> IN_VALUE (org.eclipse.jetty.http.HttpParser) │
│ [2019-07-17 19:24:16,048] DEBUG HEADER:Content-Type: application/json --> FIELD (org.eclipse.jetty.http.HttpParser) │
│ [2019-07-17 19:24:16,048] DEBUG HEADER:Content-Length --> VALUE (org.eclipse.jetty.http.HttpParser) │
│ [2019-07-17 19:24:16,048] DEBUG HEADER:Content-Length --> IN_VALUE (org.eclipse.jetty.http.HttpParser) │
│ [2019-07-17 19:24:16,048] DEBUG HEADER:Content-Length --> FIELD (org.eclipse.jetty.http.HttpParser) │
│ [2019-07-17 19:24:16,048] DEBUG HEADER:Server --> VALUE (org.eclipse.jetty.http.HttpParser) │
│ [2019-07-17 19:24:16,048] DEBUG HEADER:Server --> IN_VALUE (org.eclipse.jetty.http.HttpParser) │
│ [2019-07-17 19:24:16,048] DEBUG HEADER:Server --> FIELD (org.eclipse.jetty.http.HttpParser) │
│ [2019-07-17 19:24:16,048] DEBUG HEADER --> CONTENT (org.eclipse.jetty.http.HttpParser) │
│ [2019-07-17 19:24:16,048] DEBUG Response headers HttpResponse[HTTP/1.1 401 Unauthorized]@ec7ea09 │
│ Date: Wed, 17 Jul 2019 19:24:16 GMT │
│ Content-Type: application/json │
│ Content-Length: 32 │
│ Server: Jetty(9.4.14.v20181114) (org.eclipse.jetty.client.HttpReceiver) │
│ [2019-07-17 19:24:16,048] DEBUG Response content HttpResponse[HTTP/1.1 401 Unauthorized]@ec7ea09```