Does the cursor advances normally when you type?

Is there any text that you have typed appearing if you try to select that with the mouse or with Ctrl+A (i.e. the text is there but invisible)?

Is this only happening on the location/address bar or also in the search bar and in input fields on a web page?

Only in the address bar, cursor advances normally, and text is invisible.

Are you using an dark theme or an inverted high-contrast theme on Windows?

Start Firefox in Safe Mode to check if one of the extensions (Firefox menu button/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem.

• Switch to the DEFAULT theme: Firefox menu button/Tools > Add-ons > Appearance
• Do NOT click the Reset button on the Safe Mode start window

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

This can be a problem with the font that is used to display the text.

You can do a font test to see if you can identify corrupted font(s).

• http://browserspy.dk/fonts-flash.php?detail=1

You can try different default fonts and temporarily disable website fonts to test the selected default font.

• Tools > Options > Content : Fonts & Colors > Advanced
• [ ] "Allow pages to choose their own fonts, instead of my selections above"