Arduino IDE 1.8.12 crashes upon startup

Looks like this affects all installations of Arduino for Mac, Windows, and Linux. The next build of Arduino will address this, but for the time being, the fix is below:

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


  • remove file C:\Users\YourUsername\AppData\Local\Arduino15\package_index.json
  • remove folder C:\Users\YourUsername\AppData\Local\Arduino15\cache


  • remove file /Users/YourUsername/Library/Arduino15/package_index.json
  • remove folder /Users/YourUsername/Library/Arduino15/cache


  • remove file /home/YourUsername/.arduino15/package_index.json
  • remove folder /home/YourUsername/.arduino15/cache

Please note that the problem that prevents the IDE to start has already been fixed and it’s ready for the next release, that’s the reason why the Nightly/Beta Builds are not affected, and also the reason why we did not detect this problem earlier, sorry about that!

Solution source here

That happened me 2 days ago, and solution worked like a charm! So that was the reason of your problems in the last Livestream? Damn!

I didn’t realized that was your problem, should have say something in the chat! :sweat:

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