Pentaho Kettle MySQL Connection Errors

It’s been a minute.

I’ve been working on a number of personal projects recently and have not taken the time to document my development. I’ve learned a ton about everything from JavaScript, to ETL software Pentaho Kettle, to MySQL and Python and feel like now might be a good time to recap some of the issues I ran into during my development and also the solutions I found/devised as workarounds. More than anything, I hope this helps others that run into similar issues (and possibly also help me if by accident I run into these issues again).

The first issue I would like to recount is trouble in connecting to my GoDaddy MySQL server via Pentaho Kettle. For the longest time, this was an absolute struggle for me with no seeming explanation in site. I had set up my MySQL server on my hosting service, GoDaddy, without any issue and had been able to connect successfully via HeidiSQL. However, when I was attempting to set up my MySQL connection in Pentaho Kettle, I kept getting this absolutely horrendous error message:


Error connecting to database [devdb2] : org.pentaho.di.core.exception.KettleDatabaseException: 
Error occured while trying to connect to the database

Exception while loading class
org.gjt.mm.mysql.Driver


org.pentaho.di.core.exception.KettleDatabaseException: 
Error occured while trying to connect to the database

Exception while loading class
org.gjt.mm.mysql.Driver


    at org.pentaho.di.core.database.Database.normalConnect(Database.java:368)
    at org.pentaho.di.core.database.Database.connect(Database.java:317)
    at org.pentaho.di.core.database.Database.connect(Database.java:279)
    at org.pentaho.di.core.database.Database.connect(Database.java:269)
    at org.pentaho.di.core.database.DatabaseFactory.getConnectionTestReport(DatabaseFactory.java:86)
    at org.pentaho.di.core.database.DatabaseMeta.testConnection(DatabaseMeta.java:2464)
    at org.pentaho.ui.database.event.DataHandler.testDatabaseConnection(DataHandler.java:533)
    at sun.reflect.GeneratedMethodAccessor55.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.pentaho.ui.xul.impl.AbstractXulDomContainer.invoke(AbstractXulDomContainer.java:329)
    at org.pentaho.ui.xul.impl.AbstractXulComponent.invoke(AbstractXulComponent.java:139)
    at org.pentaho.ui.xul.impl.AbstractXulComponent.invoke(AbstractXulComponent.java:123)
    at org.pentaho.ui.xul.swt.tags.SwtButton.access$500(SwtButton.java:26)
    at org.pentaho.ui.xul.swt.tags.SwtButton$4.widgetSelected(SwtButton.java:119)
    at org.eclipse.swt.widgets.TypedListener.handleEvent(Unknown Source)
    at org.eclipse.swt.widgets.EventTable.sendEvent(Unknown Source)
    at org.eclipse.swt.widgets.Widget.sendEvent(Unknown Source)
    at org.eclipse.swt.widgets.Display.runDeferredEvents(Unknown Source)
    at org.eclipse.swt.widgets.Display.readAndDispatch(Unknown Source)
    at org.eclipse.jface.window.Window.runEventLoop(Window.java:820)
    at org.eclipse.jface.window.Window.open(Window.java:796)
    at org.pentaho.ui.xul.swt.tags.SwtDialog.show(SwtDialog.java:378)
    at org.pentaho.ui.xul.swt.tags.SwtDialog.show(SwtDialog.java:304)
    at org.pentaho.di.ui.core.database.dialog.XulDatabaseDialog.open(XulDatabaseDialog.java:115)
    at org.pentaho.di.ui.core.database.dialog.DatabaseDialog.open(DatabaseDialog.java:62)
    at org.pentaho.di.ui.spoon.delegates.SpoonDBDelegate.newConnection(SpoonDBDelegate.java:493)
    at org.pentaho.di.ui.spoon.delegates.SpoonDBDelegate.newConnection(SpoonDBDelegate.java:478)
    at org.pentaho.di.ui.spoon.Spoon.newConnection(Spoon.java:7770)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.pentaho.ui.xul.impl.AbstractXulDomContainer.invoke(AbstractXulDomContainer.java:329)
    at org.pentaho.ui.xul.impl.AbstractXulComponent.invoke(AbstractXulComponent.java:139)
    at org.pentaho.ui.xul.impl.AbstractXulComponent.invoke(AbstractXulComponent.java:123)
    at org.pentaho.ui.xul.swt.tags.SwtMenuitem.access$100(SwtMenuitem.java:27)
    at org.pentaho.ui.xul.swt.tags.SwtMenuitem$1.widgetSelected(SwtMenuitem.java:77)
    at org.eclipse.swt.widgets.TypedListener.handleEvent(Unknown Source)
    at org.eclipse.swt.widgets.EventTable.sendEvent(Unknown Source)
    at org.eclipse.swt.widgets.Widget.sendEvent(Unknown Source)
    at org.eclipse.swt.widgets.Display.runDeferredEvents(Unknown Source)
    at org.eclipse.swt.widgets.Display.readAndDispatch(Unknown Source)
    at org.pentaho.di.ui.spoon.Spoon.readAndDispatch(Spoon.java:1183)
    at org.pentaho.di.ui.spoon.Spoon.start(Spoon.java:6966)
    at org.pentaho.di.ui.spoon.Spoon.main(Spoon.java:567)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.pentaho.commons.launcher.Launcher.main(Launcher.java:134)
Caused by: org.pentaho.di.core.exception.KettleDatabaseException: 
Exception while loading class
org.gjt.mm.mysql.Driver

    at org.pentaho.di.core.database.Database.connectUsingClass(Database.java:423)
    at org.pentaho.di.core.database.Database.normalConnect(Database.java:352)
    ... 50 more
Caused by: java.lang.ClassNotFoundException: org.gjt.mm.mysql.Driver
    at java.net.URLClassLoader$1.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Unknown Source)
    at org.pentaho.di.core.database.Database.connectUsingClass(Database.java:414)
    ... 51 more

I still shudder looking at this.

Fortunately, the solution to this problem is not a complicated one. I found the answer on this post from StackOverflow. The reason the connection is failing is due to a missing MySQL Java connector library in Pentaho Kettle. This is how I solved the issue on my computer:

  1. I downloaded the most recent version of the MySQL Java Connector. (I needed to create an Oracle MySQL account in order to download this driver. To get the .zip format, I selected the Platform Independent option from the drop-down menu.)
  2. Extract the files from the downloaded .zip file and find the one labeled mysql-connector-java-5.1.34-bin.jar.
  3. Place this file into your Pentaho Kettle lib folder. The address for that should be something like C:\Program Files\pentaho\kettle\data-integration\lib.
  4. Restart Pentaho Kettle.

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