Firefox users depend on plugins and almost every browser breaks the support for the add on . Most of the time , these add ons will work perfectly fine with the update , but measures can be taken so the browser doesn't crash . to disable checking of the version of the add on , a small change it the configuration need to be done .
Ok , here it goes

Type about:config in the address bar and press [enter ] Now Right - click on the screen , then NEW > boolean . Then name it checkupdatesecurity SEt the value False .

Now restart the firefox . Now try to install that wasn't working b4 , will now work fine .

LOl...

There is a reason why they enforce this feature y'know.

Also, installing the nightly testers tool will do the same job, this is absolutely new and has been around for years.

You got the name of the preference wrong (it's extensions.checkUpdateSecurity), but even then it's the wrong pref to change.

You want to change/create the boolean pref "extensions.checkCompatibility" and set that to false.

If an extension crashes or doesn't work with newer browser versions, you're better off slapping the developer than to turn auto-updating of extensions (or the browser itself) off. Which in my not so humble opinion is a brain-dead move.

What i say You GUys ,

Your knowledge is excellent . i hearty appreciate you guys

^Doing it wrong.