Invalid library found - help please

I have just tried to compile a sketch on my new laptop and I'm getting errors relating to an invalid library. The sketch compiles fine on my desktop and I cannot see any difference in the IDE installation. The only library I invoke is Servo.h which appears to be included in the installation. Here's the error text:

Arduino: 1.8.5 (Windows 7), Board: "Arduino Nano, ATmega328P"

exec: "C:\\Users\\User\\AppData\\Local\\Arduino15\\packages\\arduino\\tools\\avr-gcc\\4.9.2-atmel3.5.4-arduino2/bin/avr-g++": file does not exist
Error compiling for board Arduino Nano.
Invalid library found in C:\Users\User\AppData\Local\Arduino15\packages\arduino\hardware\avr\1.6.21\libraries\EEPROM: C:\Users\User\AppData\Local\Arduino15\packages\arduino\hardware\avr\1.6.21\libraries\EEPROM
Invalid library found in C:\Users\User\AppData\Local\Arduino15\packages\arduino\hardware\avr\1.6.21\libraries\HID: C:\Users\User\AppData\Local\Arduino15\packages\arduino\hardware\avr\1.6.21\libraries\HID
Invalid library found in C:\Users\User\AppData\Local\Arduino15\packages\arduino\hardware\avr\1.6.21\libraries\SoftwareSerial: C:\Users\User\AppData\Local\Arduino15\packages\arduino\hardware\avr\1.6.21\libraries\SoftwareSerial
Invalid library found in C:\Users\User\AppData\Local\Arduino15\packages\arduino\hardware\avr\1.6.21\libraries\SPI: C:\Users\User\AppData\Local\Arduino15\packages\arduino\hardware\avr\1.6.21\libraries\SPI
Invalid library found in C:\Users\User\AppData\Local\Arduino15\packages\arduino\hardware\avr\1.6.21\libraries\Wire: C:\Users\User\AppData\Local\Arduino15\packages\arduino\hardware\avr\1.6.21\libraries\Wire

This report would have more information with
"Show verbose output during compilation"
option enabled in File -> Preferences.

This indicates something has gone wrong with your Arduino AVR Boards installation. To make sure it has been fully uninstalled you need to take some drastic action. Be aware this is somewhat advanced and will remove any boards you have installed via Boards Manager:

  • Click the link on the line following File > Preferences > More preferences can be edited directly in the file. This will open the Arduino15 (or similar name depending on OS) folder.
  • Delete all files and folders under the Arduino15 folder except for preferences.txt. Please be very careful when deleting things from your computer. When in doubt, back up!
  • Restart the Arduino IDE

Verify that you can now use your board before reinstalling any packages via Boards Manager.

Thanks that seems to have fixed the problem but raised a query in my mind.

The directory C:/users/user/Appdata ...... is not visible under Windows file manager but opening the file via the preferences showed it. There were two directories there and some files containing the JSON characters. After the edit you suggested those two directories are gone but still nothing visible under Windows File Manager.

Just curious - am I missing something?


Windows File Manager has the super annoying behavior of hiding some folders from you by default. You need to go into the settings and change it to not hide the system folders. While you're at it, turn off the annoying setting that hides extensions of known file types.

DOH! Sorry, I knew that but I thought I had set all those options - turns out after I restored the laptop to an earlier state it removed my selections.

Thank you for you help, much apreciated