How to import a valid copy of your electronic certificate
Skip information indexWindows - Import a copy of the certificate in Mozilla Firefox
To import a certificate in Firefox it is necessary that the copy has been made with a password since, to install it in this browser, it is mandatory to enter the "backup password". Furthermore, the copy must have been made in a valid format. The icon for a valid copy is an open envelope with a green certificate sticking out and a key, with the file extension .pfx or .p12. If the extension is not visible, right-click on the certificate icon and go to "Properties".
In Mozilla Firefox, go to "Open the application menu" (icon with three horizontal stripes located in the upper right corner of the browser), "Settings" or the "Tools" menu, "Settings".
Under "Privacy and Security", "Security", "Certificates", click the "View certificates" button.
In the "Your certificates" tab, press the "Import..." button.
Select the file that contains the copy from the location where it is saved and press the "Open" button in the "Certificate file to import" window.
The browser may ask for the master password (it is the password for the certificate store of the Mozilla Firefox browser and by default it comes unset; If you decide to establish it, keep in mind that forgetting it can cause the loss of the certificate). If there is none established, you can leave it blank, but if one has already been established, you will have to enter it to be able to continue importing the certificate. If no message about the master password appears, continue ahead.
A new window will ask for the password that was used to encrypt the backup. You accept.
If everything is correct, the certificate will appear in the Certificate Manager window, in the "Your certificates" tab.
If the copy is not valid, when imported it would be installed in the "People" tab instead of in the "Your certificates" tab and the certificate would not be valid to work on the AEAT page.