I assume that you see little boxes with the hex codes instead of the images (icon font)?

Did you check the Web Console (Firefox menu button or Tools > Web Developer) for error message about downloading fonts?

• https://developer.mozilla.org/Tools/Web_Console
• https://developer.mozilla.org/Tools/Network_Monitor

Does Firefox send a request for downloading the font files?

Does this also happen on website like these:

• https://octicons.github.com/
• https://css-tricks.com/examples/IconFont/

Can you attach a screenshot or post a link to an image hosting website?

• http://en.wikipedia.org/wiki/Screenshot
• https://support.mozilla.org/kb/how-do-i-create-screenshot-my-problem

• Use a compressed image type like PNG or JPG to save the screenshot
• Make sure that you do not exceed the maximum size of 1 MB

cor-el said

I assume that you see little boxes with the hex codes instead of the images (icon font)? Did you check the Web Console (Firefox menu button or Tools > Web Developer) for error message about downloading fonts?

• https://developer.mozilla.org/Tools/Web_Console
• https://developer.mozilla.org/Tools/Network_Monitor

Does Firefox send a request for downloading the font files? Does this also happen on website like these:

• https://octicons.github.com/
• https://css-tricks.com/examples/IconFont/

---

Can you attach a screenshot or post a link to an image hosting website?

• http://en.wikipedia.org/wiki/Screenshot
• https://support.mozilla.org/kb/how-do-i-create-screenshot-my-problem

• Use a compressed image type like PNG or JPG to save the screenshot
• Make sure that you do not exceed the maximum size of 1 MB

In the Web Console under Network, I see a lot of "304 Not Modified" entries on the GitHub link. Should I look for something specific?

On css-tricks, the icons display fine. But on the GitHub link, the icons are boxes with hex codes. (I attached a picture. It may not have attached properly, I had a little internet blink in the middle of writing this).

The icons on the developer.mozilla links are also boxes with hex code (attached picture).

By default, NoScript blocks the downloadable font because I haven't trusted the bestofmedia.com domain before. So in the first attached screenshot I probably have something similar to what you have. Once I allow scripts/fonts for that domain, it looks normal again, at least for me (second screen shot). Can you think of any reason you might be blocking that domain?

Just saw your last set of screenshots. Are you overriding web page fonts? You can double-check here:

"3-bar" menu button (or Tools menu) > Options

In the left column, click Content, then on the right side, the "Advanced" button.

Make sure you have a checkmark for "Allow pages to choose their own fonts, instead of my selections above"

Actually, in Firefox 41 and higher, even if you don't care to use a page's specified fonts, icon fonts should load, so the previous reply should not be an issue with your version.

jscher2000 said

Just saw your last set of screenshots. Are you overriding web page fonts? You can double-check here: "3-bar" menu button (or Tools menu) > Options In the left column, click Content, then on the right side, the "Advanced" button. Make sure you have a checkmark for "Allow pages to choose their own fonts, instead of my selections above"

It is checkmarked. The only blocking plugin/addon I have is AdBlockPlus. Though, it isn't blocking fonts/icons (at least, shouldn't be the main cause) as I checked Tom's Hardware directly after a Firefox Refresh, no additional addons/plugins/themes/etc. installed.

Tools menu > Help Menu > About Firefox says I'm using Firefox 42.

Attached Tom's Hardware logo picture.

Sometimes inexplicable problems are caused by corrupted program files. To rule out that kind of issue, we usually suggest:

Clean Reinstall

We use this name, but it's not about removing your settings, it's about making sure the program files are clean (no inconsistent or alien code files). As described below, this process does not disturb your existing settings. Do NOT uninstall Firefox, that's not needed.

(1) Download a fresh installer for Firefox 42.0 from https://www.mozilla.org/firefox/all/ to a convenient location. (Scroll down to your preferred language.)

(2) Exit out of Firefox (if applicable).

(3) Rename the program folder as follows:

(64-bit Windows folder names)

C:\Program Files (x86)\Mozilla Firefox

to

C:\Program Files (x86)\OldFirefox

(32-bit Windows folder names)

C:\Program Files\Mozilla Firefox

to

C:\Program Files\OldFirefox

(4) Run the installer you downloaded in #1. It should automatically connect to your existing settings.

Does a cleanly reinstalled Firefox show downloadable fonts?

Note: Some plugins may exist only in that OldFirefox folder. If something essential is missing, look in these folders:

• \OldFirefox\Plugins
• \OldFirefox\browser\plugins

jscher2000 said

Sometimes inexplicable problems are caused by corrupted program files. To rule out that kind of issue, we usually suggest: Clean Reinstall We use this name, but it's not about removing your settings, it's about making sure the program files are clean (no inconsistent or alien code files). As described below, this process does not disturb your existing settings. Do NOT uninstall Firefox, that's not needed. (1) Download a fresh installer for Firefox 42.0 from https://www.mozilla.org/firefox/all/ to a convenient location. (Scroll down to your preferred language.) (2) Exit out of Firefox (if applicable). (3) Rename the program folder as follows: (64-bit Windows folder names) C:\Program Files (x86)\Mozilla Firefox to C:\Program Files (x86)\OldFirefox (32-bit Windows folder names) C:\Program Files\Mozilla Firefox to C:\Program Files\OldFirefox (4) Run the installer you downloaded in #1. It should automatically connect to your existing settings. Does a cleanly reinstalled Firefox show downloadable fonts? Note: Some plugins may exist only in that OldFirefox folder. If something essential is missing, look in these folders:

• \OldFirefox\Plugins
• \OldFirefox\browser\plugins

A cleanly reinstalled Firefox does not show downloadable fonts.

I guess Firefox is a little cranky at me, lol.

Boot the computer in Windows Safe Mode with network support (press F8 on the boot screen) to see if that helps.

• http://www.bleepingcomputer.com/tutorials/how-to-start-windows-in-safe-mode/
• http://www.7tutorials.com/4-ways-boot-safe-mode-windows-10

Did you check the Web Console (Firefox menu button or Tools > Web Developer)?

• https://developer.mozilla.org/Tools/Web_Console

cor-el said

Boot the computer in Windows Safe Mode with network support (press F8 on the boot screen) to see if that helps.

• http://www.bleepingcomputer.com/tutorials/how-to-start-windows-in-safe-mode/
• http://www.7tutorials.com/4-ways-boot-safe-mode-windows-10

---

Did you check the Web Console (Firefox menu button or Tools > Web Developer)?

• https://developer.mozilla.org/Tools/Web_Console

I will try Safe Mode with Networking soon.

What should I look for in the Web Console?

If a downloaded font fails to load then you will usually see a specific error message about this. Each type or message has a bar at the left end in a color that corresponds with the colored dot that you see on the selection bar above the message area like orange for JavaScript and red for security related messages.

cor-el said

If a downloaded font fails to load then you will usually see a specific error message about this. Each type or message has a bar at the left end in a color that corresponds with the colored dot that you see on the selection bar above the message area like orange for JavaScript and red for security related messages.

Okay. I opened up the console and went to the GitHub link. The consoles displayed errors. I've attached a picture of them. Should I still try Safe Mode with Networking?

That message seems to originate from this code to sanitize fonts:

• http://mxr.mozilla.org/mozilla-release/source/gfx/thebes/gfxUserFontSet.cpp#584

You can check for problems with preferences. Delete possible user.js and numbered prefs-##.js files and rename (or delete) the prefs.js file to reset all prefs to the default value including prefs set via user.js and prefs that are no longer supported in current Firefox releases.

• http://kb.mozillazine.org/Preferences_not_saved
• http://kb.mozillazine.org/Resetting_preferences

You can use this button to go to the current Firefox profile folder:

• Help > Troubleshooting Information > Profile Directory: Show Folder (Linux: Open Directory; Mac: Show in Finder)
• http://kb.mozillazine.org/Profile_folder_-_Firefox

You can also try to rename (or delete) the content-prefs.sqlite file (content-prefs.sqlite.old) in the Firefox profile folder to reset website specific data.

cor-el said

That message seems to originate from this code to sanitize fonts:

• http://mxr.mozilla.org/mozilla-release/source/gfx/thebes/gfxUserFontSet.cpp#584

You can check for problems with preferences. Delete possible user.js and numbered prefs-##.js files and rename (or delete) the prefs.js file to reset all prefs to the default value including prefs set via user.js and prefs that are no longer supported in current Firefox releases.

• http://kb.mozillazine.org/Preferences_not_saved
• http://kb.mozillazine.org/Resetting_preferences

You can use this button to go to the current Firefox profile folder:

• Help > Troubleshooting Information > Profile Directory: Show Folder (Linux: Open Directory; Mac: Show in Finder)
• http://kb.mozillazine.org/Profile_folder_-_Firefox

You can also try to rename (or delete) the content-prefs.sqlite file (content-prefs.sqlite.old) in the Firefox profile folder to reset website specific data.

I renamed prefs.js to prefs.js.old (I don't have any numbered ones, and I don't have any users.js files), and did the same with content-prefs.sqlite. Icons are now back, I can see everything at the GitHub link, and Tom's Hardware is normal (and so is every site that uses custom fonts/icons). This also solved another problem I was having at a specific site, yay!

Any idea what caused this, so I know what not to do in the future?

Thank you for your help, cor-el and jscher2000!

Edit: The problem has returned. The error in the Console remains the same. I have not changed anything, just customized the toolbar area to include the Sync button. I haven't even added the theme I had.

What if you rename prefs.js again, then assuming Firefox behaves normally after a restart, use a text comparison program to see the differences between the old prefs.js and the live one. I generally use WinMerge for such things.

http://winmerge.org/

Did you reboot the computer or only closed and restart Firefox?

jscher2000 said

What if you rename prefs.js again, then assuming Firefox behaves normally after a restart, use a text comparison program to see the differences between the old prefs.js and the live one. I generally use WinMerge for such things. http://winmerge.org/

WinMerge pointed out a lot of differences between the newest prefs.js and the newest old one, where I hadn't changed anything at all. Can I link to a .zip with both files in Dropbox?

cor-el said

Did you reboot the computer or only closed and restart Firefox?

I only closed and reopened Firefox a few minutes later.

Yes, you can link to a ZIP file here if you like.

jscher2000 said

Yes, you can link to a ZIP file here if you like.

https://dl.dropboxusercontent.com/u/102020907/Prefs.zip

The old prefs file is the file that was good, then went bad without me changing anything. The new prefs file is one that lets me see icons properly.

I don't see any font-related differences.

I'm not sure what this is:

user_pref("gfx.blacklist.suggested-driver-version", "15.2010.1151.0");

but in the Question Details > More System Details next to your original post it says:

direct2DEnabledMessage: [u'tryNewerDriver', u'15.2010.1151.0']

This article suggests how to update if there are known problems with your current graphics card driver software: Upgrade your graphics drivers to use hardware acceleration and WebGL.