> For the complete documentation index, see [llms.txt](https://docs.pentaho.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.pentaho.com/install/9.3-install/use-hadoop-with-pentaho/big-data-issues/general-configuration-problems/connection-problems.md).

# Connection problems

| Symptoms                                                                                               | Common Causes                                                                                                                                                                                                                                                               | Common Resolutions                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
| ------------------------------------------------------------------------------------------------------ | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Hostname does not resolve.                                                                             | <ul><li>No hostname has been specified.</li><li>Hostname/IP Address is incorrect.</li><li>Hostname is not resolving properly in the DNS.</li></ul>                                                                                                                          | <ul><li>Verify that the Hostname/IP address is correct.</li><li>Check the DNS to make sure the Hostname is resolving properly.</li></ul>                                                                                                                                                                                                                                                                                                                                                                                   |
| Port number does not resolve.                                                                          | <ul><li>Port number is incorrect.</li><li>Port number is not numeric.</li><li>The port number is not necessary for HA clusters.</li><li>No port number has been specified.</li></ul>                                                                                        | <ul><li>Verify that the port number is correct.</li><li>Determine whether your cluster has been enabled for high availability (HA). If it has, then you do not need a port number. Clear the port number and retest the connection.</li></ul>                                                                                                                                                                                                                                                                              |
| Cannot connect to the cluster.                                                                         | <ul><li>Firewall is a barrier to connecting.</li><li>Other networking issues are occurring.</li><li>A <code>\*-site.xml</code> file is invalid.</li><li>The address or port number information is incorrect for the cluster or service you are trying to connect.</li></ul> | <ul><li>Verify that a firewall is not impeding the connection and there are no other network issues.</li><li>Verify that all <code>\*-site.xml</code> files are well-formed, valid XML.</li><li>Verify that the addresses and port numbers for the cluster and services are correct.</li></ul>                                                                                                                                                                                                                             |
| Windows failure message: “`java.io.FileNotFoundException: HADOOP_HOME` and `hadoop.home.dir are unset` | <ul><li>A configuration setting is required. Windows cannot locate the <code>%HADOOP\_HOME%\bin\winutils.exe</code> file and the <code>Hadoop\_Home</code> directory is not set.</li></ul>                                                                                  | Please follow the instructions at <https://cwiki.apache.org/confluence/display/HADOOP2/WindowsProblems> and set the environment variable *%HADOOP\_HOME%* to point to the directory path containing `WINUTILS.EXE`.                                                                                                                                                                                                                                                                                                        |
| Cannot access a Hive database (Secured Clusters Only).                                                 | <ul><li>To access Hive, you need to set two database connection parameters using the PDI client.</li></ul>                                                                                                                                                                  | <ol><li>Open the <code>hive-site.xml</code> file on the Hive server host. Note the values for the <strong>kerberos.principal</strong> and the <strong>sasl.qop</strong> parameters, then close the file.</li><li>Start the PDI client and open the Database Connection window.</li><li>Click <strong>Options</strong>, and add the <strong>sasl.qop</strong> and <strong>principal</strong> parameters. Set them to the same values as they are in the <code>hive-site.xml</code> file. Save and close the file.</li></ol> |


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