If you have not cleared your caches recently, an error might occur causing the scroll bar not to load. Try clearing your caches and refreshing the web page.

If the web page is short and has less than one page of text, a scroll bar will not appear. Hold down "Ctrl" and press "+" repeatedly until the scroll bar appears.

jerieggg said

with version 70.0.1 (64-bit), I find that I lose the vertical scroll bar if I hit the back button to visit a previous page in a website, this happens with every site, I have to reload the page to get it back. Really annoying.

Hmm, I can't think of a good reason for that. Some sites may end up in an odd place when you go Back, but it shouldn't happen on every site.

Could you compare in Firefox's Safe Mode? In its Safe Mode, Firefox temporarily deactivates extensions, hardware acceleration, any userChrome.css/userContent.css files, and some other advanced features to help you assess whether these are causing the problem.

If Firefox is not running: Hold down the Shift key when starting Firefox. (On Mac, hold down the option/alt key instead of the Shift key.)

If Firefox is running: You can restart Firefox in Safe Mode using either:

• "3-bar" menu button > "?" Help button > Restart with Add-ons Disabled
• (menu bar) Help menu > Restart with Add-ons Disabled

and OK the restart.

Both scenarios: A small dialog should appear. Click "Start in Safe Mode" (not Refresh).

Any difference?