Hello, I have been having some issues with Firefox recently. My version is 50.1.0, and I am running a fully up to date x64 Windows 10 Professional pc with way more than enough resources. I haven't had any issues until recently when I began learning how to develop a WebExtension. I used the examples provided by Mozilla called Your First/Second WebExtension. Both of these worked fine for me when I followed the code and how to put them together and run them. Next I began work to develop my own WebExtension. I borrowed some code from the examples to create the popup window on the toolbar. I haven't had any issues with writing the html, css, and php code that I will use in my WebExtension. I then started to add Javascript to call functions to get information from the user's active tab. I could not get this to work even though I thought I understood the documentation for what I was trying to use. Then I tried to simplify my code and output a basic javascript function. I got the code to do what I expected when running the html page standalone, but when I tried to use the exact same code in my WebExtension, I found that it would not work. After a lot of confusion and time I finally decided that I was not able to run any javascript code in my created web extension. So I decided to backtrack. I tried the earlier examples from Mozilla that I got to work, and now both of those wont work either. For "borderify," also known as Your First WebExtension, I can not even open the addon in firefox. When I try to open the manifest.json, it tells me I am choosing the wrong file type. When I try the Second WebExtension, the manifest.json loads the addon properly, but the javascript used in it is completely broken, almost like the code does not exist at all. Then i started getting issues with regular functions of firefox. Menus would open but i could not get them to close (right click and toolbar). The close/fullscreen/minimize buttons at the top right of the browser lost their function, but i could still browse pages just fine (with javascript working). I used the "alt" button on my keyboard to expose the hidden menus at the top of the browser to check for an update, but the alt key would only work very intermittently. I had to press it maybe 40 times in a row before i could access any of the file menus. These issues would persist with browser restarts as well as Windows OS restarts. I checked the about:config page to confirm that javascript was still enabled, it was. I then performed a full browser reset, clearing all data, resetting all settings to default, and removing all plugins, etc. with some success. My issues with menus not closing stopped, and the alt function works normally now, but my javascript is still broken. Even after recreating the webExtension projects from mozilla identically, just as before, I cannot get the javascript to work at all. TL;DR = Javascript is not working in user created/temporary plugins Sorry that was so long, but I am really confused here so I tried to be detailed. If anyone has ideas, I would love to hear/try them out. I feel like there must be something that is blocking my WebExtensions' javascript, but I can't understand what it could possibly be, since I have not tampered with any related settings before or after. -Thanks for your time <3