great add on!
for those who are having issues as of recent
try to go to about:config in the url bar
xpinstall.signatures.required
set to false
its a temp work around..until developer fixes
tutorial in link
https://www.ghacks.net/2015/06/19/how-to-disable-the-firefox-40-add-on-signing-requirement/

I absolutely love this extension. And just being a day without it really shows how well it actually works on blocking all the annoying things on the internet. I hope Firefox gets their shit together and fixes this issue that won't allow the downloading of this extension. I left chrome for Firefox and I'm now starting to regret that decision.

Ublock Origin has Dead on FF 56
Mozilla terminated Add-ons support for my Firefox 56

*** Today Update 11/05/2019 ***

uBlock Origin v1.19.0 has Revived on my Firefox 56 !!!

Thank you!

Great Add-on !!! 5 (Five Stars)

ok