Issues related to fonts
This article describes issues caused by missing font support and missing or corrupted fonts and other issues where websites do not display properly like text that overlaps or you see gibberish or diamonds with a '?' or boxes with hex code.
Boxes with hex code
If you see little boxes with hex code (numbers) then that means that you do not have an Unicode font installed that can display those characters.
Firefox displays the hex code instead so you can do a look up in a table to see which character is meant to be displayed.
If you have such a problem then first make sure that you have installed font support for those languages on your Operating System (See Check for font support).
It is also possible that you do not have a font installed that covers that Unicode plane. See Unicode support
Check for font support
For Windows also see Microsoft Windows XP - Install complex script and right-to-left language files (microsoft.com)
East Asian websites
If the problem is with East Asian (Chinese, Japanese, Korean) websites then verify that your operating system has support for East Asian languages.
See this Wikipedia article: Wiki: Help:Multilingual support (East Asian)
See also Installing_East_Asian_language_support_under_Windows and Firefox will not display East Asian characters (Mozilla Support)
If the problem is with Indic (complex script) websites then verify that your operating system has support for complex script languages.
See this Wikipedia article: Wiki: Help:Multilingual support (Indic)
See also Indian sites display incorrectly (Mozilla Support)
For generic Unicode support and Unicode fonts see these Wikipedia articles:
- Mapping of Unicode characters - Wikipedia, the free encyclopedia
- Unicode plane - Wikipedia, the free encyclopedia
- Alan Wood’s Unicode Resources
Bold or Italic text or text in a different font
If you see bold or italic text or text in a strange or wrong font then a possible cause is a missing or corrupted font that causes Firefox to switch to another font.
In such cases you can first try to reinstall core fonts like Arial, Tahoma, Times New Roman, Verdana.
See also Some text shows up bold after upgrade (Mozilla Support)
- Open Control Panel > Fonts
- Choose > File > Install new Font
- Browse to the "C:\windows\fonts" folder
- Select the font(s) that you want to refresh
- Click Install to install and refresh all selected fonts
See also How to install or remove a font in Windows (microsoft.com)
If a web server sends the wrong encoding and you see a diamond with a '?' or other strange characters then you can try a different encoding via "View -> Character Encoding" like UTF-8 if UTF-16 or a Western encoding is selected. You can try "View -> Character Encoding -> Auto-Detect -> Universal" to see if that makes Firefox select a working encoding. You can check the encoding send by the server and the content encoding in a meta header in the document via "Tools -> Page Info -> General".
If text in a larger font size shows as gibberish then a possible cause is the Helvetica or Geneva bitmap font or another (bitmap) font that can't be displayed by Firefox in the specified font-size and is displayed as garbage instead.
You can test that by zooming out (View > Zoom > Zoom Out, Ctrl + -) to make the text smaller. Another possible test is to disable the fonts specified by websites: Tools -> Options > Content : Fonts & Colors: Advanced > [ ] "Allow pages to choose their own fonts, instead of my selections above"
You will have to uninstall (remove) all variants of that not working font to make Firefox use another font or find a True type version of that font that works better.
See also Wikipedia: Computer (Bitmap) font
If the text is too large or overlaps or extends out of a text container then try to reset the text (page) zoom via "View -> Zoom -> Reset" (Ctrl+0; zero).
If you made changes to the minimum font size then try a lower setting (default is none). A too high minimum font size can cause such issues.
Tools -> Options -> Content: Fonts & Colors: Advanced -> Minimum Font Size
Tools -> Options -> Content: Fonts & Colors: Advanced -> "Allow pages to choose their own fonts, instead of my selections above"
The default font setting is for the selected encoding.
If you need to increase (or decrease) the font size on websites then look at these extensions:
UTF-16 encoding in the title bar
If you see East-Asian (CJK) code in the Firefox title bar and the Taskbar icon then that can be caused by Firefox switching to UTF-16 encoding and interpreting UTF-8 code as UTF-16. Most part of the Unicode UTF-16 plane in mapped to CJK characters, so it very likely that such an manifest itself as East Asian characters.
The RealPlayer Browser Record Plugin extension (Tools -> Add-ons -> Extensions) has been reported to cause this issue.
Do not confuse that extension with the RealPlayer plugin (Tools -> Add-ons -> Plugins) that plays media files. The extension adds some extra features like saving media files.
You can disable/remove the RealPlayer Browser Record Plugin extension in the RealPlayer Preferences (RealPlayer: Tools -> Preferences -> Download & Recording)
See Standard diagnostic - Firefox: Extension issues
If Indic pages display garbage then check if there is a link on the page to download a special font. If there is such a link then download and install that font. Reload the page and see if that works. You can also use the Padma extension Padma (addons.mozilla.org) to add font support for a lot of Indic websites. See also Padma (mozdev.org)
For troubleshooting font issues on Mac you can do a check for corrupted fonts and other font issues.
- CreativeTechs Tips: Garbled Fonts Troubleshooting Guide
- Font Book 2.0 Help: Checking for damaged fonts
For issues on OS X 10.6 (Snow Leopard) also see these pages: