Fix – Unexpected response received from the server

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Unexpected response received from the server
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If you are struggling to connect Hive/Impala service with your ODBC client, then I hope this article, Will help to understand the issue and solution for it

This error usually happens if you are trying to connect to Hive/Impala from a Linux client using ODBC driver and you will be seeing the below error

[Cloudera][DriverSupport] (1110) Unexpected response received from server. Please ensure the server host and port specified for the connection are correct and confirm if SSL should be enabled for the connection.

Why we are seeing this ERROR and some common causes

This issue can occur if the Wrong Port/FQDN for Hiveserver2/Impala daemon is used Or If SSL is not configured properly for the client.

Common causes

  1. Version Incompatibility: The client and server versions may not be compatible. Ensure both the client and server are updated to versions that support each other.

    To check the latest version, use the below link
    Hive – https://www.cloudera.com/downloads/connectors/hive/odbc
    Impala – https://www.cloudera.com/downloads/connectors/impala/odbc
  1. Configuration Issues: There might be Incorrect configuration settings on either the client or server side can cause communication problems. Double-check the connection strings, IP addresses, port numbers, and any other relevant configuration details.
  2. Server Overload or Downtime: The server might be experiencing a high load or might be down temporarily. Check the server status and any relevant logs for error messages or warnings.
  3. Network Issues: There could be a network issue preventing the client from communicating with the server. This could be a firewall blocking the connection, network congestion, or incorrect routing. Verify the network settings and test the connection using tools like ping or telnet to ensure there’s a clear path between the client and the server.
    Example: telnet <hostname> <port>
  4. Driver Issues: The ODBC/JDBC driver might be outdated, corrupted, or not properly installed. Try redownloading and reinstalling the driver.
  5. SQL Query or Command Issues: If the error occurs in response to a specific SQL query or command, there might be a syntax error or a feature not supported by the server. Review the query or command for any potential issues.

Resolution:

To begin with, We need to make sure the connection string is appropriate

  • Hiveserver2/Impala daemon hostname or port number mentioned in the connection string/DSN should be valid

    This can be verified by running the command “netstat -plant | grep <port>” in the Hiveserver2/Impala daemon host
  • If SSL is enabled for Hive/Impala, do as follows:
    1. Ensure that the SSL certificates of the services are imported to the client.
    2. Verify if SSL is set to ‘true’ on the client DSN/connection string.
    3. AuthMech has to be mentioned properly:
      • AuthMech=”3″ (This means you are trying to connect using username and password and SSL can be used).
      • AuthMech=”2″ (This means you are trying to connect only using a username; SSL is not available in this.
      • AuthMech=”1″ (This means you are using Kerberos setup)

Example connection String:

Impala connection String, Where I am using Kerberos, Similar, We can reuse the string for Hive

'jdbc:impala://<Impala coordinator hostname>:21050/;AuthMech=1;KrbRealm=<realm>;KrbHostFQDN=<FQDN>

NOTE: Refer to the doc, If you are using a different OS or auth type

If you are still seeing the issue post correct the connection string, Check the below troubleshooting steps to proceed further

Common troubleshooting steps:

  • Check Logs: Look at both client and server logs to find any additional information about the error. The logs might provide specific details on what went wrong.
  • Update Software: Make sure both your client and server software are up to date.
  • Review Configuration: Double-check all connection and configuration settings.
  • Test Network Connectivity: Use network testing tools to verify connectivity between the client and the server.
  • Consult Documentation: Sometimes, specific servers or databases have unique requirements or known issues with certain versions of clients. Reviewing the official documentation might provide insights or solutions.
    Example: For Impala ODBC refer to this doc, for each driver you will have separate documentation

Conclusion:

In conclusion, conquering Hive-ODBC connection woes boils down to diligence: update drivers, check settings, and ensure compatibility. It’s a test of patience but hugely rewarding. Embrace the challenge, refine your troubleshooting skills, and enjoy seamless data flow. Here’s to overcoming tech hurdles with ease!

Happy Learning !!

Jerry Richard
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