How do I install a previous version of Firefox?

[Hayli]

Firefox apparently updated to a Beta version. Which the xKit add-on doesn't work with. I need this add-on, so could someone please help me?
@Jazylne: Thank you for your suggestion. I'd prefer to do something a bit less drastic.
@David Mark: How do I do that?
@Sum Tung Wong: I'm very confused on what you are suggesting.

@Mark: I unistalled, and downloaded from the page you hyperlinked. I'm still receiving the same message " Beta versions of Firefox are known to cause problems with XKit. If you still want, you can click here to download XKit 7 manually, but XKit might refuse to boot up or cause problems. Unfortunately, I can not provide support for the version of Firefox you use until it comes out of beta. Make sure other versions of XKit and dashboard themes are disabled before you install XKit."

[Jazylne]

You could try restoring your computer to a previous point.

[David Mark]

By restoring your previous version of Firefox.

[Sum Ting Wong]

you can get any version of ff on filehippo you want or do the following and make any addon compatible with ff add the extension nightly tester and checkcompatibility 1.3 then open about:config type compat in search field and look for nightly.disableCheckCompatibility; change true to false unless ff changes radically addons work

[Matt]

The current release version of firefox can't just update to beta. It doesn't work that way as they are two different programs with different updates for each.

If you have accidentally installed the beta version, just uninstall it via control panel and download the current release from here - https://www.mozilla.org/en-US/firefox/all/

Also xKit is constantly updating to stay compatible with new browser updates. Make sure you have the latest update for xKit.

[Pravallika]

go to the following link
https://ftp.mozilla.org/pub/mozilla.org/.../releases/

1) find the version number you wanna install (look out for b1/b2/ etc, they are beta versions of that particular release )

2) click on the version you need, you would be taken to page to choose the installer for Windows 32 bit / 64 bit /Linux etc. Choose the correct installer

3)Uninstall the current version that's buuging you and install the version you downloaded.