Firefox won't export your digital certificate: the fix is in Windows

A user reports that Firefox returned an error when exporting his FNMT certificate. Another forum member told him to export it from the Windows certificate manager instead.

English · Original discussion in Spanish · Published

Firefox won't export your digital certificate: the fix is in Windows
The Firefox bug that blocks digital certificates

An error when saving the PKCS #12 backup file. That is the message Firefox returns, according to one user, when he tries to export his digital certificate from the FNMT (Spain's national mint, which issues citizens' digital certificates) and finds that the browser flatly refuses. It happens right as he is packing up: the computer where the certificate is installed is «about to die» and the user needs to move it to another machine because he uses it every day. The FNMT, in its instructions 1377, suggests deleting Firefox's root certificates before exporting. It doesn't work. The error persists. And the alternative of installing the originals in another browser on the same computer doesn't cut it either: the system doesn't recognize them because they are not backups.

What to do when Firefox won't export the digital certificate

The solution that unblocks the problem doesn't go through Firefox. It goes through the Windows certificate manager, a tool that has existed since XP and that in Windows 10 still works without fuss. From there you can export the certificate by checking the «export the private key» option and assigning it a password. That's confirmed by the person who tried it after days of failed attempts: «I can't BELIEVE it. You saved my life in two lines». The Windows manager exports the certificate to a file that can then be imported on any other computer. The key lies in the private key: without it, the certificate is a seal without a signature.

Why the FNMT doesn't explain this

The FNMT publishes guides and FAQs, but the solution to the export failure in Firefox appears nowhere. Some argue that the administration assumes citizens already know their way around the system's certificate store. Others point out that the problem lies with Firefox, which has been accumulating glitches with FNMT certificates. According to the official documentation cited in the thread, Firefox works correctly with the FNMT root certificate from version 51 onwards, from January 2017. From then on, users report that updates sometimes fix the problem and sometimes make it worse. One participant sums it up bluntly: «Firefox usually gives trouble with certificates even when you export them using the pc's system».

The myth that the certificate only works on one computer

At service counters and on support phone lines, a false idea keeps coming up: that the digital certificate only works on the computer where it was requested. It isn't true. It can be exported and installed on several machines, on a USB drive or on a mobile phone. The confusion comes from mixing two different things: the application process, which does require doing it from the same browser, and later use, which has no strings attached. A real exception is the cryptographic cards that the FNMT and Telefónica sold years ago: there is no way to export the private key from those. For all other cases, the certificate is portable.

The alternative many overlook

If the certificate was installed only in Firefox, it won't be in Chrome or Edge. Each browser has its own store. Chrome and Edge read the system store; Firefox uses its own. That's why exporting from the Windows manager works even when Firefox refuses. The resulting file can be saved in Google Drive, on a USB drive or in your email, with a password you won't forget. Some recommend putting it in a RAR archive with a password different from the certificate's. And for those handling many certificates, the advice is repeated: use the Windows manager as the main store, because Firefox doesn't let you sort or search them properly.



The digital certificate is the entry key to Spain's e-government services. When it fails, citizens are locked out of their own home. The solution exists, it's free and it's hidden in a menu almost nobody visits. The surprising fact: the tool that solves the problem has been installed in Windows for more than two decades. Nobody mentions it until someone stumbles upon it.

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Summary of a discussion on Burbuja.info - Foro de economía, actualidad y política., translated from Spanish and reviewed before publication. Read the full discussion (41 replies).

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