Java ClassNotFoundException

Whenever I open a website that uses Java, I get a ClassNotFoundException. I have tried reinstalling Java, removing temporary files, running Ccleaner after the uninstall but the issue still remains.

 

ClassNotFoundException

You deploy a new version of your application into production environment, hit the application’s URL and get a 500 error with a long error stack and nasty “java.lang.ClassNotFoundException” in bold at the top.

“Class Not Found” exceptions could be quite tricky to troubleshoot because of the complexity of Java Web applications and application servers they run on. An average web application nowadays comes bundled with dozens of jar file (and probably thousands of classes). An average application server’s classpath is many pages long. Not to mention separately deployed libraries containing jar files shared by a group of applications. There should be little surprise that it is quite common for all these different jars and classloaders to clash with each other, get out of sync or become otherwise corrupt and mis-configured.

http://myarch.com/classnotfound

 

The odd thing is that this happens to all java applications. Is there a guide to delete all Java related files so I can reinstall it and not have this problem? I have uninstalled it before but the problems is still there so I'm guessing that there's still a configuration file somewhere that's causing this problem.

 

Greetings, rainbows, and welcome to MajorGeeks...

I'm curious: what's your operating system version and Service Pack #, and what version of Internet Explorer are you using?

Couple of quickies:

1. Try an alternate browser such as Firefox, see if your symptoms change.

2. Navigate to Control Panel > Internet Options > Security, set your controls for maximum protection (which should disable Java), see if your symptoms change.

 

I'm using Windows Vista SP2 and IE 9.
1. This issue occurs on all browsers including Firefox and Chrome.
2. In this case, the content that requires Java doesn't display at all.

 

Does that even happen on the Java site, when you click on Verify Java Version: http://www.java.com/en/download/installed.jsp ?

 

Yes, it does.

 

Try JavaRA to remove Java http://singularlabs.com/software/javara/
I would not recommend using the update tool on version 2 of JavaRa. I used it a few weeks ago (XP computer) and I got the wrong version of Java so I had to do some cleanup.

Download the latest version of Java v7 update 10 and put it on your desktop to install after JavaRA removes things.
http://www.oracle.com/technetwork/java/javase/downloads/index.html
JRE, you don't need JDK.

 

Interestingly enough, everything was fine when JavaRA installed Java 6 Update 6, it worked fine. However, when I manually installed Java 7 Update 10, it stopped working and returned the same error.

 

Never ran Vista so I have no way of testing, sorry.

In FF, do the following:
disable plugins.click_to_play in about:config

1. type about:config in the address bar
2. type plugins in the filter box
3. scroll down to plugins.click_to_play

My value is false and I have no issues in XP (only one computer in the house has Java installed). Check that yours is set to false also.

 

[Edit] I meant to say that I'm using Windows 7. Sorry if there was any confusion.

 

I just checked and the value is false.

 

I'm trying to find the safest version 6 of Java.
v6, update 6 has vulnerabilities http://secunia.com/advisories/product/12878/

Here are the archived version 6 downloads
http://www.oracle.com/technetwork/j...ds/java-archive-downloads-javase6-419409.html

 

As far as I'm aware, all of them have security vulnerabilities so I want to use Java 7 but it has the error which only appears when I use Java 7.:confused

 

Well, I'm seeing that some older programs can't use Java 7; perhaps that's part of your problem.

Looks like v6 update 35 should be avoided
http://www.oracle.com/technetwork/j...ds/java-archive-downloads-javase6-419409.html

Try 6 update 37, again look for JRE not JDK.

 

Thanks. Java 6 is working fine.

 

I was using the Java Control Panel to check for updates to see if I could update to Java 7 Update 10 and it went out without problems and I no longer had the ClassNotFoundException. However, I if removed Java 6 using JavaRA and installed Java 7 Update 10, manually, I got ClassNotFoundException on all applets.:confused