[solved] Library Manager Error Message

I get the following error message:

package_index.json file signature verification failed
java.lang.RuntimeException: cc.arduino.contributions.SignatureVerificationFailedException: package_index.json file signature verification failed
 at cc.arduino.contributions.libraries.ui.LibraryManagerUI.lambda$onUpdatePressed$0(LibraryManagerUI.java:212)
 at java.lang.Thread.run(Thread.java:745)
Caused by: cc.arduino.contributions.SignatureVerificationFailedException: package_index.json file signature verification failed
 at cc.arduino.contributions.packages.ContributionsIndexer.parseIndex(ContributionsIndexer.java:94)
 at processing.app.BaseNoGui.initPackages(BaseNoGui.java:487)
 at processing.app.Base$8.onIndexesUpdated(Base.java:1328)
 at cc.arduino.contributions.libraries.ui.LibraryManagerUI.lambda$onUpdatePressed$0(LibraryManagerUI.java:210)
 ... 1 more
Index error: could not find referenced tool name=arm-none-eabi-gcc version=4.8.3-2014q1 packager=arduino
Index error: could not find referenced tool name=arm-none-eabi-gcc version=4.8.3-2014q1 packager=arduino
Index error: could not find referenced tool name=CMSIS version=4.5.0 packager=arduino
Index error: could not find referenced tool name=CMSIS version=4.5.0 packager=arduino
Index error: could not find referenced tool name=CMSIS version=4.5.0 packager=arduino

I completely de-installed Arduino, removed the Arduino folder in Documents, and installed Arduino 1.8.3, but still get this error. What should I do?

The error message is not revealing the cause of the error.

Try this:

  • Click the link following File > Preferences > More preferences can be edited directly in the file - this should open a folder named Arduino15 or similar.
  • Delete all files in that folder other than preferences.txt. Please be very careful when deleting things on your computer. When in doubt back up!
  • Restart the Arduino IDE.
  • Tools > Board > Boards Manager
  • Wait for downloads to finish.
  • Click "Close".

Hopefully after that the error will no longer occur.

Yes, this helps. Arduino startup, Boards Manager and Library Manager work flawlessly again. Thank you!