Icons on Confluence Top Navigation Bar Rendered as Letters in Internet Explorer & Firefox

Steps to Reproduce

• Launch Internet Explorer
• Navigate to Internet Options >> Security
• Do the following for all zones:
  1. Click Custom Level...
  2. In the resulting Security Settings prompt, look for the Downloads section, and set Font download to Disable
  3. Click OK and then Apply (remember to repeat these 3 steps for all zones)
• Restart the OS
• Navigate to Confluence after the restart, and notice that the Confluence Top Nav Bar now looks like this:
  

The issue is also affecting FF browser

Workaround for IE:

• In Internet Explorer, navigate to Tools >> Internet Options >> Security
• Do the following for all zones:
  1. Click Custom level...
  2. In the resulting Security Settings prompt, look for the Downloads section, and set Font download to Enable.
  3. Click OK and then Apply (remember to repeat these 3 steps for all zones)
• If this does not work, then there could be other reasons causing this. Best would be to try to download the font pack manually via: http://<yourConfluenceURL>/s/en_GB-1988229788/4226/d7686547091e645d7b0285207c0b86be721c74eb.1/5.0/_/download/resources/com.atlassian.auiplugin:aui-experimental-iconfont/atlassian-icons.ttf to see if indeed, Confluence is serving that font pack correctly.
• Customers running Confluence in SSL will need to add the following to <CONFLUENCE_INSTALLATION>/conf/server.xml (within the <Context ... /> element):

  <Valve className="org.apache.catalina.authenticator.NonLoginAuthenticator"
         disableProxyCaching="true" securePagesWithPragma="false" />
  

  After that, restart Confluence. Thanks to kevin.hughes for this suggestion

• Installation of Java with IE plugin

Workaround for FF:

• Type about:config in FF URL bar
• Search for "browser.display.use_document_fonts". The value is set to 0
• Reset it to the default value 1 to fix the problem