title: Issues upgrading to schema-registry 2.0.1
body: <p>we are currently trying to upgrade from schema-registry 1.0.1 to 2.0.1. We see this is working prior to the upgrade with the following versions: kafka_2.10 version 0.9.0.2.4.0.0, kafka-avro-serializer version 2.0.1, avro version 1.7.7</p>
  
  <p>After the upgrade the same requests successful earlier now fail with HTTP 404 errors:</p>
  
  <pre><code>[2016-07-26 10:11:05,748] INFO  - - [26/Jul/2016:10:11:05 +0000] "POST //subjects/thing-avro-key/versions HTTP/1.1" 404 49  4 (io.confluent.rest-utils.requests:77)
  
  
  2016-07-26 11:23:00.908 b.s.d.executor [ERROR] 
  org.apache.kafka.common.errors.SerializationException: Error registering Avro schema: "string"
  Caused by: io.confluent.kafka.schemaregistry.client.rest.exceptions.RestClientException: HTTP 404 Not Found; error code: 404
          at io.confluent.kafka.schemaregistry.client.rest.RestService.sendHttpRequest(RestService.java:157) ~[stormjar.jar:?]
  </code></pre>
  
  <p>We checked with CURL and are able to post a schema using an example:</p>
  
  <pre><code>curl -X POST -i -H "Content-Type: application/vnd.schemaregistry.v1+json"  --data '{"schema": "{\"type\": \"string\"}"}' http://localhost:8081/subjects/Kafka-value/versions
  </code></pre>
  
  <p>We then thought Avro schema: "string" might be the problem, so created a ThingKey schema but still getting a similar error: </p>
  
  <pre><code>2016-07-26 11:47:31.347 b.s.d.executor [ERROR]
  org.apache.kafka.common.errors.SerializationException: Error registering Avro schema: {"type":"record","name":"ThingKey","namespace":"com.x.platform.messages","doc":"A thing identifier for partitioning","fields":[{"name":"thing_id","type":{"type":"string","avro.java.string":"String"},"doc":"Thing identifier"}]}
  Caused by: io.confluent.kafka.schemaregistry.client.rest.exceptions.RestClientException: HTTP 404 Not Found; error code: 404
  </code></pre>
  
  <p>We are using the following code to publish the message:</p>
  
  <pre><code>ProducerRecord&lt;String, SpecificRecordBase&gt; producerRecord = new ProducerRecord&lt;&gt;(topic, getMessageKey(msg), extractAvroMessage(msg));
  producer.send(producerRecord);
  
  public SpecificRecordBase extractAvroMessage(KafkaMessage msg) 
  public String getMessageKey(KafkaMessage msg) 
  </code></pre>
  
  <p>Any ideas or suggestions much appreciated.</p>
  
  <p>Thanks,
  Ross</p>
  
  <hr>
  
  <p><strong>Update</strong>: Fixed - the issue was due to an additional slash in the request path which is causing failures due to stricter validation in version 2.0.1. Full details at: <a href="https://github.com/confluentinc/schema-registry/issues/388" rel="nofollow">https://github.com/confluentinc/schema-registry/issues/388</a></p>