[SOLVED] NullPointerException when trying to uninstall NetBeans 12.0

NullPointerException when trying to uninstall NetBeans 12.0

I'm trying to uninstall NetBeans 12.0, but the wizard throws the following exception at startup:

Exception: java.lang.NullPointerException: null

The log says this:

[2020-08-11 14:03:20.249]:     initializing product registry properties
[2020-08-11 14:03:20.249]:     exiting -- org.netbeans.installer.product.Registry.initializeRegistry():170
[2020-08-11 14:03:20.253]:     ... loading registry from file:/C:/Users/Kai/.nbi/registry.xml
[2020-08-11 14:03:20.311]:     entering -- org.netbeans.installer.product.Registry.loadProductRegistry():981
[2020-08-11 14:03:20.312]:     validating previous installations
[2020-08-11 14:03:20.378]:         NameResolver - to parse C:\Program Files\NetBeans 8.2
[2020-08-11 14:03:20.392]:         NameResolver - to parse C:\Program Files\NetBeans-12.0
[2020-08-11 14:03:20.396]:         NameResolver - to parse C:\Program Files\NetBeans-12.0
[2020-08-11 14:03:20.404]:         NameResolver - to parse C:\Program Files\NetBeans 8.2\bin\jre
[2020-08-11 14:03:20.407]:         NameResolver - to parse C:\Program Files\NetBeans-12.0
[2020-08-11 14:03:20.410]:         NameResolver - to parse C:\Program Files\NetBeans-12.0
[2020-08-11 14:03:20.414]:         NameResolver - to parse C:\Program Files\NetBeans-12.0
[2020-08-11 14:03:20.417]:         NameResolver - to parse C:\Program Files\NetBeans-12.0
[2020-08-11 14:03:20.424]:         NameResolver - to parse C:\Program Files\NetBeans 8.2
[2020-08-11 14:03:20.425]:     ... validating installations finished
[2020-08-11 14:03:20.425]:     exiting -- org.netbeans.installer.product.Registry.loadProductRegistry():981
[2020-08-11 14:03:20.425]:     ... loading registry from resource:data/registry.xml
[2020-08-11 14:03:20.434]:     entering -- org.netbeans.installer.product.Registry.loadProductRegistry():981
[2020-08-11 14:03:20.434]:     validating previous installations
[2020-08-11 14:03:20.434]:         NameResolver - to parse C:\Program Files\NetBeans 8.2
[2020-08-11 14:03:20.435]:         NameResolver - to parse C:\Program Files\NetBeans-12.0
[2020-08-11 14:03:20.437]:         NameResolver - to parse C:\Program Files\NetBeans-12.0
[2020-08-11 14:03:20.437]:         NameResolver - to parse C:\Program Files\NetBeans 8.2\bin\jre
[2020-08-11 14:03:20.438]:         NameResolver - to parse C:\Program Files\NetBeans-12.0
[2020-08-11 14:03:20.439]:         NameResolver - to parse C:\Program Files\NetBeans-12.0
[2020-08-11 14:03:20.440]:         NameResolver - to parse C:\Program Files\NetBeans-12.0
[2020-08-11 14:03:20.441]:         NameResolver - to parse C:\Program Files\NetBeans-12.0
[2020-08-11 14:03:20.442]:         NameResolver - to parse C:\Program Files\NetBeans 8.2
[2020-08-11 14:03:20.443]:     ... validating installations finished
[2020-08-11 14:03:20.443]:     exiting -- org.netbeans.installer.product.Registry.loadProductRegistry():981
[2020-08-11 14:03:20.447]:     An unexpected exception happened in thread Thread-2
[2020-08-11 14:03:20.448]:     java.lang.NullPointerException
[2020-08-11 14:03:20.448]:      at org.netbeans.installer.utils.helper.Version.equals(Version.java:69)
[2020-08-11 14:03:20.448]:      at org.netbeans.installer.product.Registry.changeStatuses(Registry.java:600)
[2020-08-11 14:03:20.448]:      at org.netbeans.installer.product.Registry.initializeRegistry(Registry.java:184)
[2020-08-11 14:03:20.448]:      at org.netbeans.installer.wizard.components.actions.InitializeRegistryAction.execute(InitializeRegistryAction.java:53)
[2020-08-11 14:03:20.448]:      at org.netbeans.installer.wizard.components.actions.netbeans.NbInitializationAction.execute(NbInitializationAction.java:69)
[2020-08-11 14:03:20.448]:      at org.netbeans.installer.wizard.components.WizardAction$1.run(WizardAction.java:103)
[2020-08-11 14:03:20.448]:     ... show message dialog
[2020-08-11 14:03:20.448]:         title: Critical Error
[2020-08-11 14:03:20.448]:         message: An unexpected exception happened in thread Thread-2
[2020-08-11 14:03:20.449]:         
[2020-08-11 14:03:20.449]:         Exception:
[2020-08-11 14:03:20.449]:           java.lang.NullPointerException:
[2020-08-11 14:03:20.449]:           null
[2020-08-11 14:03:20.449]:         
[2020-08-11 14:03:20.449]:         You can get more details about the issue in the installer log file:
[2020-08-11 14:03:20.449]:          C:\Users\Kai\.nbi\log\20200811140318.log
[2020-08-11 14:03:27.074]:     ... dialog closed

Does anyone have an idea how to fix this error or uninstall NetBeans 12.0 using another method?

Solution

After some trial and error, the following method worked for me:

Go into your user directory (C:\Users\YourUsername\) and locate the .nbi directory inside of it
Delete the .nbi directory (or move it to another location)
Run the NetBeans 12.0 uninstaller

After that, the uninstall wizard couldn't find the registry keys for NetBeans 12.0 and stopped the uninstalling process. To fix this, I did the following:

Delete your Netbeans 12.0 directory (C:\Programs\NetBeans 12.0\)
Install NetBeans 12.0 again with the install wizard
Uninstall NetBeans 12.0 via Windows 10 settings

Finally, I was able to uninstall NetBeans 12.0 with no Nullpointer Exception.