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

how to change firefox from starting in compatibilty mode?

  • 2 replies
  • 1 has this problem
  • 25 views
  • Last reply by FredMcD

more options

since changing from windows 8.1 to windows 10 i keep getting a pop up when using Mozilla Firefox saying that the program has started in compatibility mode and it can lead to undesirable effects so i should disable the compatibility settings, how do i do this?

since changing from windows 8.1 to windows 10 i keep getting a pop up when using Mozilla Firefox saying that the program has started in compatibility mode and it can lead to undesirable effects so i should disable the compatibility settings, how do i do this?

All Replies (2)

more options

Hi, right click on the Firefox Desktop icon (or Program) > Properties > Compatibility tab.

Also note that you have 2 versions of Shockwave Flash - the oldest should be removed.

If your question is resolved by this or another answer, please take a minute to let us know. Thank you.

more options

Shockwave Flash 19.0 r0 Shockwave Flash 15.0 r0
Having more than one version of a program may cause issues. You must remove the older programs. Then get the current full installer.

Note: Edge on Win10 does not use ActiveX version but its own Flash.

Flash: Grab the uninstaller from here: Uninstall Flash Player | Windows Uninstall Flash Player | Mac

Then reinstall the latest version.

Flash Player Version 19.0.0.226
https://www.adobe.com/products/flashplayer/distribution3.html
Note: Windows users must download the “Internet Explorer” and “Plugin-based browsers” installers.

Adobe still offers Flash 18.0.0.255 as its extended support release further down


Scribe said

Hi, right click on the Firefox Desktop icon (or Program) > Properties > Compatibility tab.

Clear all selections on this tab.