For those who are using Firefox and the NoScript addon, the Arduino plugin install will fail even if you allow all scripts.
The problem stems from a component of NoScript called the ABE (Application Boundaries Enforcer) which is always active unless #1 you disable the item in options > advanced > ABE or #2 you disable the addon completely.
Also starting Firefox by holding SHIFT will turn off all the addons for testing.
I hope this helps a few out there, good luck. ![]()