When an add-on prevents Firefox from working properly it is put on the blocklist by Mozilla. These add-ons cannot be installed on Firefox.

If you try to install a blocklisted add-on, Firefox will display a message that will inform you of the danger. Common examples of this message are "The extension ... is known to be dangerous, and can't be installed."

If the add-on was already installed before being blocklisted, it will be disabled and the Add-ons window will display the text "Disabled for your protection."

View the Add-ons Blocklist...