Arduino IDE does not launch


I have been using Arduino IDE 1.8.12 in my PC for over a month without any trouble.

Suddenly, now, when launching arduino the flash screen appears (I can see that it is opening packages), the window closes but the IDE does not appear.

I have been using arduino V 1.8.12

My OS is Win7 64 bit

I have tried the following things:

1- Move the ...->Documents\Arduino folder to other place (for a possible library issue). When launching, the program creates again the folder Arduino (empty), but the IDE does not appear.

2- I uninstalled Arduino and installed it again without any change

3- I installed the last Java version

4- I executed from a CMD environment the arduino_debug.EXE file In this case I obtained a message like:

"java.lang.NullPointerExeption at cc.arduino.contributions.packages.ContributionsIndexer.ParseIndex"

The msg continues pointing three times to[number] with different numbers (483, 273 and 150)

I will appretiate some help or orientation with this


I emailed Arduino support about this, we'll see what happens. Problem has been all over the forum today.

I worked on this for 2 hours last night about 2AM New York time.

Tried re-installing IDE, deleting all my settings, ... and eventually tracked it down to reading the board library from the internet package_index.json in Arduino15. So tried shutting off virus checking and switch to IPv4 ... which got it partially working.

It seems to work fine 8 hours later. It must have been a problem with the package_index on the internet. ??

Please see this post
Then ensure you are or were not affected.

I am also having the same problem since yesterday afternoon. The IDE even worked, but after closing and trying to reopen the problem appeared. I tried with another user and the same thing happened, it worked the first time and then it didn’t work anymore. The messages that Arduino_debug. exe are the same (OS Windows 7):

C: \ Program Files (x86) \ Arduino> arduino_debug.exe
Picked up _JAVA_OPTIONS: -Xmx512M
Loading configuration …
Initializing packages …
at cc.arduino.contributions.packages.ContributionsIndexer.parseIndex (
at (
at (
at (

C: \ Program Files (x86) \ Arduino>

This problem hit us at around 4PM Phoenix time yesterday. Can’t open v1.18.12 on our Windows 10. Have latest Java. The IDE small advert appears for 1 second then disappears - nothing. Deleted our Programs Files (x86) versions and installed Windows App version. This worked on one of our laptops but the other.

When running CMD window in the appropriate Windows Apps area under Program Files\Windows Apps, I get this

C:\Program Files\WindowsApps\ArduinoLLC.ArduinoIDE_1.8.33.0_x86__mdqgnx93n4wtt>arduino_debug.exe
Set log4j store directory C:\Users\jackw\Documents\ArduinoData
Loading configuration…
Initializing packages…
at cc.arduino.contributions.packages.ContributionsIndexer.parseIndex(

Arduino Support sent this out:

We had a problem on our package_index.json file which caused the current error and it has prevented the IDE to start. Now the package_index.json file has been fixed, but to recover a working installation you must delete once again the package_index.json and restart the IDE as usual.

You can find the package_index.json usually in the following folders:

[color=#2b2e2f]remove file C:\Users\YourUsername\AppData\Local\Arduino15\package_index.json
remove folder C:\Users\YourUsername\AppData\Local\Arduino15\cache[/color]


[color=#2b2e2f]remove file /Users/YourUsername/Library/Arduino15/package_index.json
remove folder /Users/YourUsername/Library/Arduino15/cache[/color]


[color=#2b2e2f]remove file: /home/YourUsername/.arduino15/package_index.json
remove folder /home/YourUsername/.arduino15/cache[/color]

Please note that the problem that prevents the IDE to start has already been fixed for the next releases, that's the reason why the Nightly/Beta Builds are not affected, and also the reason why we did not detect the problem earlier,