Hi jrswartz1, there is a known issue in Firefox 77 affecting users who force-disable the multiprocess feature (e10s) using a method such as:

• setting a preference in about:config to prevent multi-process
• using a Windows environment variable to disable multi-process

You either can allow multiprocess to run, which most modern computers can handle and improves security and stability, or you can temporarily roll back a feature which depends on multi-process for properly decoding text.

• Remove environment variable: https://support.mozilla.org/questions/1289760
• Setting change: https://support.mozilla.org/questions/1290884

By the way, how can you view the animated GIF page by page? Is there some kind of player for those that can pause on a frame?

hello jrswartz1

some other affected users tied the issue to the McAfee site advisor extension -

1. please try to disable or remove that in case you have it present.

follow this link:

Disable or remove Add-ons

2. You can use the set command to create a temporary environment variable.

   open command prompt window
   change to installation directory
   type "set MOZ_FORCE_DISABLE_E10S=1" and press enter
   type "firefox.exe" and press enter 

How to use set command : http://www.computerhope.com/sethlp.htm

I hope resolve the problem please reply me back.

Setting the "set MOZ_FORCE_DISABLE_E10S=1" did not fix my problem. However jschar2000 had posted in another thread the following which did work. Or, the combination of the two worked.

As a side, I used IrfanView to display multi-page GIF files.

"Hi Felis-2, someone on Reddit mentioned turning off a new feature to resolve this issue. There's a note in the code that this preference means "use DocumentChannel with parent process' sDocShell" but I don't know the consequences of changing it, so you may want to research it further:

(1) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button accepting the risk.

(2) In the search box in the page, type or paste ppdc and pause while the list is filtered

(3) Double-click the browser.tabs.documentchannel.ppdc preference to switch the value from true to false

You may need to do a regular exit and restart of Firefox before that takes effect.

More info on about:config: Configuration Editor for Firefox."