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Hostname Change Error

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While staging to rebuild the Oracle DB Console (Oracle Enterprise Manager – OEM), I needed to check something in my MySQL instance and ran into the following error after changing the machine’s hostname for that OEM test. The message basically says that MySQL Workbench can’t resolve the connection.

The dialog error provides an excellent note, which lists the actual error as the first thing to check. The dialog follows:

This lists the text of the error dialog:

Your connection attempt failed for user '<user_name>' from your host to server at <server_name>:3306:
  Unknown MySQL server host '<server_name>' (0)
1 Check that mysql is running on server <server_name>
2 Check that mysql is running on port 3306 (note: 3306 is the default, but this can be changed)
3 Check the student has rights to connect to <server_name> from your address (mysql rights define what clients can connect to the server and from which machines)
4 Make sure you are both providing a password if needed and using the correct password for <server_name> connecting from the host address you're connecting from

Navigate to Database -> Manage Connections… in the menu. This opens a dialog where you can manage the details of a connection.

It opens the following dialog page:

The Test button lets you retest whether the connection works. The error message raised by the test, noted below, is not nearly as detailed as the previous error message.

Inspecting the Parameters tab below, you see the hostname value McLaughlinMySQL. The actual hostname is mclaughlinsql. You need to replace the displayed value with the correct value.

After making the change, click the Test Connection button. A correct change prompts you for the user’s password and when successfully entered yields the following dialog.

Hope this helps a few folks resolve the problem when the machine hostname changes.

Written by maclochlainn

September 2nd, 2012 at 10:23 pm