If you have been having problems with Java, and you have followed some of the instructions on the forums you may find that you no longer can get Java to install because of an error.

When you attempt to run the java installer file you receive the message:

When you click Yes to the above question you receive the error:

This problem is caused because the Windows Installer information for a previous installation of Java has been removed or damaged, but the related registry keys are still present causing the Java installer to think it is already installed.

This problem can be caused if you used the "Windows Installer Cleanup Utility" to remove the Java™ entries without first uninstalling Java properly.

To fix this problem you must remove the two places in the registry that the Java installer looks at in order to determine if it is already installed. By removing these entries, the Java installer will begin a new installation instead of attempting to repair the old corrupt installation.

Updated Feb. 26th, 2010 -- Created a universal fix for all versions of Java 6

This problem is confirmed in Windows XP, Windows Vista, and Windows 7.

Because the registry keys that need to be removed are different for each version of Java, I have created a batch file you can download to find and remove the entries automatically.

Here's how to fix Java:

• If you are able, uninstall all previous versions of Java in add/remove programs in your control panel.
• Next, you may download the current version of Java here: http://java.com/en/download/manual.jsp
  I recommend that you use the offline installer version.
• Now, download the fix:  fixjava.zip ( 336bytes ) Number of downloads: 211
  

  Open the fixjava.zip file, extract and run the file fixjava.bat . If you are using Windows Vista, or Windows 7 you must right-click the fixjava.bat file and choose "Run As Administrator". If you do not see the run as administrator option, drag the fixjava.bat file to your desktop and then try to run as administrator from there.
  The batch file will run briefly without confirmation.

• You may now install Java without any errors about it already being installed.

The contents of the batch file are listed below:


This fix will work on Windows XP, Windows Vista, and Windows 7 for both 32-bit and 64-bit versions of the Java 6 runtime environment.

If you have any further issues please post a reply in this thread.

This post has been edited by appleoddity: Feb 26 2010, 03:08 AM

Because your problem occured as a result of using the Windows Installer Cleanup Utility, you should be able to run the registry fix I provided in my initial post and have the problem resolved.

The fix will remove this registry key: HKEY_LOCAL_MACHINE\SOFTWARE\JavaSoft\Java Runtime Environment
This is left behind after the windows installer cleanup.

The problem occurs because the Java setup program you download looks for "evidence" of a current installation of Java on your computer (the above registry key). If it finds it, it will attempt to run the currently installed "installer file" rather than reinstalling with the fresh installer you downloaded. If the installer cleanup was used, those installer files are deleted, so the problem occurs. It makes no sense to me why Java would do this, and hopefully someone from the development team will see this and fix the problem once and for all.

This post has been edited by appleoddity: Sep 12 2009, 07:47 AM