NetBeans could not start due to wrong JVM version, incompatible library and missing files

NetBeans could not start on a Xubuntu Linux system.

It displayed a splash screen, wrote the message Initializing for a few seconds and then quit.


The original distribution was Xubuntu 16.04 LTS which had been updated to Xubuntu 18.04 LTS.

Tried starting NetBeans from terminal and got these warnings:

WARNING: An illegal reflective access operation has occurred
WARNING: Illegal reflective access by org.netbeans.ProxyURLStreamHandlerFactory (file:/usr/share/netbeans/platform18/lib/boot.jar) to field
WARNING: Please consider reporting this to the maintainers of org.netbeans.ProxyURLStreamHandlerFactory
WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
WARNING: All illegal access operations will be denied in a future release


Decided to check the startup activity with:

strace netbeans 2> netbeans_strace.txt

Noticed that NetBeans was looking for configuration files in 3 locations:

stat("/usr/share/netbeans/8.1/etc/netbeans.conf", {st_mode=S_IFREG|0644, st_size=2958, ...}) = 0
stat("/etc/netbeans.conf", {st_mode=S_IFREG|0644, st_size=2958, ...}) = 0
stat("~/.netbeans/8.1/etc/netbeans.conf", 0x7ffc7aae8df0) = -1 ENOENT (No such file or directory)


Decided to look for other files under: ~/.netbeans/8.1/

Found log files under: ~/.netbeans/8.1/var/log/

Part of: ~/.netbeans/8.1/var/log/messages.log

Product Version = NetBeans IDE 8.1 (Build 20180221-debian-8.1)
Java Home = /usr/lib/jvm/java-11-openjdk-amd64
java.lang.SecurityException: setContextClassLoader
at java.base/jdk.internal.misc.InnocuousThread.setContextClassLoader(


Discovered that NetBeans 8.1 requires JDK 8.

Found JDK 8 under:


Created the folder:


Then created the configuration file:


With a single line:



This seemed to help somewhat, because the splash screen continued until:

Turning on modules…

But then it quit again…


Found and examined: ~/.netbeans/8.1/var/log/messages.log

Noticed this part:

Product Version = NetBeans IDE 8.1 (Build 20180221-debian-8.1)
Java Home = /usr/lib/jvm/java-8-openjdk-amd64/jre
INFO [org.netbeans.modules.netbinox]: Install area set to file:/usr/share/netbeans/8.1/
at org.eclipse.osgi.baseadaptor.BaseAdaptor.initializeStorage(
at org.eclipse.osgi.framework.internal.core.Framework.<init>(
at org.eclipse.osgi.framework.internal.core.EquinoxLauncher.internalInit(
at org.eclipse.osgi.framework.internal.core.EquinoxLauncher.init(
at org.eclipse.osgi.launch.Equinox.init(
at org.netbeans.modules.netbinox.Netbinox.init(Unknown Source)
at org.netbeans.core.netigso.Netigso.prepare(Unknown Source)
at org.netbeans.NetigsoHandle.turnOn(Unknown Source)
at org.netbeans.ModuleManager.enable(Unknown Source)
INFO [null]: Last record repeated again.
at org.netbeans.core.startup.ModuleList.installNew(Unknown Source)
at org.netbeans.core.startup.ModuleList.trigger(Unknown Source)
at org.netbeans.core.startup.ModuleSystem.restore(Unknown Source)
at org.netbeans.core.startup.Main.getModuleSystem(Unknown Source)
INFO [null]: Last record repeated again.
at org.netbeans.core.startup.Main.start(Unknown Source)
at Source)


Found this site, which seemed to describe this part of the problem:


Checked the installed version of libequinox-osgi-java which was: 3.9.1-1

Downloaded: libequinox-osgi-java_3.8.1-10_all.deb



Installed the package with:

sudo dpkg -i libequinox-osgi-java_3.8.1-10_all.deb

Held the package at the old version with:

sudo apt-mark hold libequinox-osgi-java


Tried starting NetBeans again, but it still failed to start.

Found errors in: ~/.netbeans/8.1/var/log/messages.log


!ENTRY org.eclipse.osgi 4 0 2018-10-15 22:49:29.510
!MESSAGE Error reading configuration: Unable to create lock manager.
!STACK 0 Unable to create lock manager.


Tried running NetBeans as root with:

sudo netbeans

It started up without crashing…


It was still unable to start under the regular user account.

Noticed that it had created some files with root as owner:

!ENTRY org.eclipse.osgi 4 0 2018-10-15 23:05:36.425
!MESSAGE Error reading configuration: Permission denied
!STACK 0 Permission denied
at Method)
at org.eclipse.osgi.storagemanager.StorageManager.initializeInstanceFile(


Decided to change the file permissions with:

sudo chown $USER:$USER ~/.netbeans/ -R

sudo chown $USER:$USER ~/.cache/netbeans/ -R


This was the last step. After this NetBeans could finally start normally again.


If NetBeans fails to start on Ubuntu/Xubuntu 18.4 LTS try these things:

  • Check and change used JDK to version 8.
  • Downgrade libequinox-osgi-java package from 3.9.1-1 to 3.8.1-10 and hold/pin it.
  • Run NetBeans as root once.
  • Change NetBeans file permissions to normal user permissions.

Android Studio build failing due to Gradle NullPointerException

I recently experienced problems with Android Studio, where it would no longer clean or rebuild a particular project.


The Gradle Console showed this message:

FAILURE: Build failed with an exception.

* What went wrong:
java.lang.NullPointerException (no error message)

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output.


Tried selecting: File menu -> Invalidate Caches / Restart…

Unfortunately this had no effect.


Looked for more details by building from a commandline with the suggested options:

gradlew build --stacktrace --debug > build_debug_log.txt 2> build_debug_error.txt


(It was neccessary to log standard output and error output separately, because otherwise they would get mixed up)

However the Gradle output still didn’t explain clearly why the build process was failing.


Found a suggestion to delete the .gradle folder in the project folder here:


I closed the Android Studio project, moved the .gradle folder outside of the project folder and reopened the Android Studio project.

This solved the problem!

It was now possible to clean and rebuild the project again.


If Android Studio refuses to build due to NullPointerException from Gradle, try removing or moving the .gradle folder from the affected project.