unabla to run arduino 1.6.12

Development Tools IDE 1.x
3

Try this:

  • Start Arduino IDE 1.6.7
  • Tools > Board > Boards Manager
  • Wait for the downloads to complete
  • Click the "Close" button
  • Now try Arduino IDE 1.6.12

If that doesn't work do this:

  • Start Arduino IDE 1.6.7
  • File > Preferences
  • Select all text in the box next to "Additional Boards Manager URLs:" and copy it
  • Paste it here and I'll take a look at the files at those URLs to see if one has a formatting issue that causes Arduino IDE 1.6.12 to not start.

Ballscrewbob:
C:\Users\yourname\AppData\Local\ArduinoCreateAgent
or
C:\Users\yourname\AppData\Roaming\ArduinoCreateAgent

That should be Arduino15, not ArduinoCreateAgent. ArduinoCreateAgent is for the web based IDE, Create.