Cannot open help in matlab, "Exception in thread "AWT-EventQueue-0" java.lang.​NullPointe​rException​"

I cannot open the help with the button or even by command. If I type some command I get the hint, and I can get more help, but when trying to open the "Open help Browser" it complains.

Error: Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException at com.mathworks.mde.help.HelpBrowser$1.whenHelpBrowserExists(HelpBrowser.java:169) at com.mathworks.mde.help.HelpBrowser$HelpBrowserRunnable.run(HelpBrowser.java:1335) at com.mathworks.mde.help.HelpBrowser$HelpBrowserRunnable.doHelpBrowserAction(HelpBrowser.java:1323) at com.mathworks.mde.help.HelpBrowser$HelpBrowserRunnable.access$300(HelpBrowser.java:1314) at com.mathworks.mde.help.HelpBrowser.invoke(HelpBrowser.java:178) at com.mathworks.mde.help.ClassicHelpBrowserHandler.invoke(ClassicHelpBrowserHandler.java:19) at com.mathworks.mde.help.HelpBrowserBridge.invoke(HelpBrowserBridge.java:48) at com.mathworks.mlservices.MLHelpServices.invoke(MLHelpServices.java:42) at com.mathworks.mde.desk.MLDesktop$HelpProductPageAction.actionPerformed(MLDesktop.java:2676) at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2028) at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2351) at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:387) at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:242) at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:236) at java.awt.AWTEventMulticaster.mouseReleased(AWTEventMulticaster.java:272) at java.awt.AWTEventMulticaster.mouseReleased(AWTEventMulticaster.java:272) at java.awt.AWTEventMulticaster.mouseReleased(AWTEventMulticaster.java:272) at java.awt.Component.processMouseEvent(Component.java:6414) at javax.swing.JComponent.processMouseEvent(JComponent.java:3275) at com.mathworks.mwswing.MJButton.processMouseEvent(MJButton.java:347) at java.awt.Component.processEvent(Component.java:6179) at java.awt.Container.processEvent(Container.java:2084) at java.awt.Component.dispatchEventImpl(Component.java:4776) at java.awt.Container.dispatchEventImpl(Container.java:2142) at java.awt.Component.dispatchEvent(Component.java:4604) at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4618) at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4279) at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4209) at java.awt.Container.dispatchEventImpl(Container.java:2128) at java.awt.Window.dispatchEventImpl(Window.java:2492) at java.awt.Component.dispatchEvent(Component.java:4604) at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:717) at java.awt.EventQueue.access$400(EventQueue.java:82) at java.awt.EventQueue$2.run(EventQueue.java:676) at java.awt.EventQueue$2.run(EventQueue.java:674) at java.security.AccessController.doPrivileged(Native Method) at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:86) at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:97) at java.awt.EventQueue$3.run(EventQueue.java:690) at java.awt.EventQueue$3.run(EventQueue.java:688) at java.security.AccessController.doPrivileged(Native Method) at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:86) at java.awt.EventQueue.dispatchEvent(EventQueue.java:687) at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:296) at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:211) at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:201) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:196) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:188) at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)

Matlab R2012a, 64bit, mac PS: I already tried to gave permission to the folders (.matlab and Documents/MATLAB/)

[Tejas]

Hello Angela,

The following can help in troubleshooting the issue with Help Browser in MATLAB:

1) What happens when you execute the following:

>> web www.google.com

This command should open a Google search page from MATLAB. If there is a problem then you might get an error with this command.

2) What version of Java are you using? You can use the following commands to find this information. (The version of Java should be the same as the one that your Mac OS has.)

>> version -java
>> ver

3) The file 'classpath.txt' could be shadowed by another file of the same name. To check if this is the case, execute:

>> which classpath.txt

The output is a single file location that should look similar to the following:

C:\Program Files\MATLAB\R2012a\toolbox\local\classpath.txt

If the file location is different, then the 'classpath.txt' that is shipped with MATLAB is being shadowed. To resolve this issue, simply rename the 'classpath.txt' (that is not shipped with MATLAB) to another name.

4) If you have modified the file 'classpath.txt' (that is shipped with MATLAB) then you may have to restore it.