This site will have limited functionality while we undergo maintenance to improve your experience. If an article doesn't solve your issue and you want to ask a question, we have our support community waiting to help you at @FirefoxSupport on Twitter and/r/firefox on Reddit.

Search Support

Avoid support scams. We will never ask you to call or text a phone number or share personal information. Please report suspicious activity using the “Report Abuse” option.

Learn More

The rendering engine often fails to draw pages correctly.

more options

Text pages are often littered with black bars that obscure the lettering, almost like redaction. Refreshing the page usually solves the issue. Also, the bookmarks bar will often present with a pattern of dark gray and light gray blocks, which resolves when the mouse cursor passes over them. The attached images show what I mean.

Text pages are often littered with black bars that obscure the lettering, almost like redaction. Refreshing the page usually solves the issue. Also, the bookmarks bar will often present with a pattern of dark gray and light gray blocks, which resolves when the mouse cursor passes over them. The attached images show what I mean.
Attached screenshots

All Replies (2)

more options

Start Firefox in Safe Mode {web Link} by holding down the <Shift>
(Mac=Options)
key, and then starting Firefox. A small dialog should appear. Click Start In Safe Mode (not Refresh).

Is the problem still there?

more options

Thanks, FredMcD. I have not observed the effect since starting in safe mode. I guess, from the disappearance of my add-ons, that this means an add-on is the likely culprit, and that the next step is to introduce them one by one until the issue recurs. I'll try that and see what happens. It might take a day or three to report the results.