What does the error message say?

What does the error message say?

you can see it in the screenshot. like "the addon could not be downloaded due to a connection problem".

The link you have have provided seems to be taking to the page for the google chrome addon. I tried downloading and installing the social blade addon from Mozilla using this: https://addons.mozilla.org/en-US/firefox/addon/unofficial-social-blade/?src=search

Got successfully installed, and looks to be working fine. You may want to try.

Hmm, it seems okay for me. The install button on their site pulls this file:

https://addon.socialblade.com/firefox/social_blade-2.4.9-fx.xpi

Does that link give you a connection error?

There is security software like Avast, Kaspersky, BitDefender and ESET that intercept secure connection certificates and send their own.

https://support.mozilla.org/en-US/kb/firefox-cant-load-websites-other-browsers-can

https://support.mozilla.org/en-US/kb/firefox-and-other-browsers-cant-load-websites

https://support.mozilla.org/en-US/kb/secure-connection-failed-error-message

https://support.mozilla.org/en-US/kb/connection-untrusted-error-message

Websites don't load - troubleshoot and fix error messages

http://kb.mozillazine.org/Error_loading_websites

What do the security warning codes mean

The link you have have provided seems to be taking to the page for the google chrome addon. I tried downloading and installing the social blade addon from Mozilla using this: https://addons.mozilla.org/en-US/firefox/addon/unofficial-social-blade/?src=search Got successfully installed, and looks to be working fine. You may want to try.

yeah but its not official addon. "seems to be taking to the page for the google addon" okay, but why the page say "Social Blade Firefox Addon" when its for chrome or doesnt work with firefox, i dont understand that.

There is security software like Avast, Kaspersky, BitDefender and ESET that intercept secure connection certificates and send their own.

i have deactivate my ESET security and try again but doesnt work for me. i have try to install it in the microsoft edge chromium and it works fine but i dont want use this browser i mean only for this addon.

You could try "Plan B": download the extension to disk and install from the Add-ons page.

Can you right-click > Save Link As on the link:

https://addon.socialblade.com/firefox/social_blade-2.4.9-fx.xpi

If you can save the Add-on, the method to install from disk is on the Add-ons page. Either:

• Ctrl+Shift+a (Mac: Command+Shift+a)
• "3-bar" menu button (or Tools menu) > Add-ons
• type or paste about:addons in the address bar and press Enter/Return

In the left column of the Add-ons page, click Extensions. On the right side, find the large "gear" button, click that, and choose "Install Add-on from File". Then point Firefox to the .xpi file you downloaded.

You could try "Plan B": download the extension to disk and install from the Add-ons page.

task completed ! thank you!