This article does not say. https://support.mozilla.org/en-US/kb/use-master-password-protect-stored-logins

What length do you have in mind?

I don't think that there is a hard coded limit, so a few hundred characters shouldn't be a problem if you can remember and type such a long MP without problems.

Thanks for your replies. I have a 35 character password I'd like to use.

The reason I'm asking is because I had a problem on another web service where I changed my password to one that was apparently to long for their system to handle, and I ended up getting locked out... neither the new or the old password would work. So I just want to avoid losing access to all my stored passwords if this sort of thing would happen again.

I realize that most services don't stipulate the maximum number of characters allowed, but if this information is available for Firefox, I'd like to know before I try resetting the password.

Thanks if you can help.

Maybe be cautious if you use special accented or Unicode characters in the password and make sure it works in the Password Manager or on other cases when you are prompted for the MP.

Thanks.

Just wondering if I back up my Profile, which I believe includes the Password Manager, if I get locked out I could just replace the existing Profile with the one I backed up to restore it back to the original password.

Would that work?

Yes. You can also;

These can't get your data back, but will help in the future.

These add-ons can be a great help by backing up and restoring Firefox

https://addons.mozilla.org/en-US/firefox/addon/febe/ FEBE (Firefox Environment Backup Extension)

FEBE allows you to quickly and easily backup your Firefox extensions, history, passwords, and more. In fact, it goes beyond just backing up -- It will actually rebuild your saved files individually into installable .xpi files. It will also make backups of files that you choose.

https://addons.mozilla.org/en-US/firefox/addon/opie/ OPIE

Import/Export extension preferences

Thanks all for your help. I put FF 56.0 on an old computer and tried a 32 character master password that worked no problem. I think 32 mixed characters should be secure enough.

Just wondering, if I ever have to restore my profile from a back up, do I just delete the folder in C:\Users\user 1\AppData\Roaming\Mozilla\Firefox\Profiles, and then paste the backed up folder in its place?

You only need logins.json (saved username and password) and key3.db (encryption key including the MP).

You need the profiles.ini file as well because that is the profile registry and that is where Firefox looks for profiles. Without a profiles.ini that has this profile listed you won't be able to use a copied profile. In that case you would have to use the use the Profile Manager to create a new profile or edit profiles.ini.

• click "Choose Folder" in the Profile Manager
• browse to the location of a lost profile to recover this profile and register it in the Profile Manager

Note that you should never use "Choose Folder" to specify a folder that already contains files that do not belong to Firefox (i.e. only use "Choose Folder" to recover an orphaned profile that isn't listed in the Profile Manager)

Thanks cor-el.

I did a search on the folder [C:\Users\user 1\AppData\Roaming\Mozilla\Firefox\Profiles] for "profiles.ini" and it did not show up. Where do I find it?

And I found the "login.json" file, and a file named "key3" but not "key3.db."

Windows hides some extensions. You can change the settings to not hide thru Folder Options.