User Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:56.0) Gecko/20100101 Firefox/56.0 Build ID: 20170722072631 Steps to reproduce: Installed 64-bit version of Firefox for Windows. Open the addon manager. Actual results: Icons for numerous addons are missing. Both WebExtension and legacy addons are missing icons, while the icons that are there are also both WebExtension and legacy. Example addons with missing icons: Emoji keyboard, Greasemonkey, Stylus, uBlock Origin/webext, Unicode Keyboard Expected results: Icons should all be present.
Simply installing Firefox and some of the named extensions isn't enough to reproduce this, can you please provide more detail? eg, what version of Windows, what version of Firefox, were the extensions installed before upgrading from 32-bit to 64-bit? Also if you could check the browser console when this happens and include anything you see there, that would be helpful: https://developer.mozilla.org/en-US/docs/Tools/Browser_Console
Windows 7, 64-bit Version of firefox shown in the initial post — July 22 Nightly build. Extensions were already installed, yes. I just re-installed the 64-bit version of Firefox from July 28, however, and the icons are present. Reinstalling the July 22 build, the icons are still present there as well. It seems whatever caused the original error has been fixed, or cleaned up in the July 28 handling of the profile.
Okay, thanks for taking time to report this. If it happens again and you can gather any additional details please feel free to re-open or file a new bug.