Firefox Developer Edition fails to load cross-origin script

(Thomas Deinhamer) #1

On firefox developer edition (58.0b8, 64-Bit) on Window 10 (10.0.16299 Build 16299) has problems loading the script from, the web developer tools console prints Loading failed for the <script> with the source "". but it actually doesn’t tell why it wasn’t able to load it.

This seems to work in Chrome after all.

Does someone have an idea what’s going on here? Is this some kind of cross-origin issue/bug?

Thanks a lot!

(Julien Wajsberg) #2

Hey Thomas,

I believe you use an adblock and/or you enabled Firefox tracking protection.

On my own Firefox I reproduce your issue but once I disable both uBlock and Tracking protection for this page, I don’t get the error anymore.

Hope this helps :slight_smile:


(Thomas Deinhamer) #3

Oh my! Of course, I didn’t think about it at all. Thanks a lot for the hint! :smiley:


I’m running into a similar issue, but with Cloudflare. This is a WebExtensions add on that I’m porting from Chrome. It works perfectly fine on Chrome. I do not have an Ad Blocker installed and I tested fully disabling Tracking Protection. I still get the error:

Content Security Policy: The page’s settings blocked the loading of a resource at

I’ve tried adding

“permissions”: ["<all_urls>", …

to my manifest as suggested elsewhere, but the CORS issue persists. As stated above, this is not an issue on Chrome.

Is there another reason that this could be happening, other than an ad blocker or Tracking Protection?

Firefox 59.0.2 (non-private mode)
Mac OSX 10.12.6