If you are struggling with a font icon error after upgrading your w3speedster WordPress plugin to the 7.09 version. Here is the step-by-step process to fix it:
1. Visit your w3speedster plugin from the general settings.
2. Open the CSS tab of the plugin, and scroll down to Custom CSS to load with preload CSS at last.
3. Now that you are in the Custom CSS to load with preload CSS functionality, you’ll find the Font Icon CSS entity without a backslash.
4. Add Backslash (\) in the entity of the font icon 4. CSS and Click on Save Changes. This will fix your Font Error. Assist from the picture below.
5. Make sure to clear your w3speedster cache and HTML cache after you’ve saved changes.