How do I create master password where I neglected to do so on installation?
Upon installation, I was unaware that a master password had to be created. Now, I cannot create one because I have no existing master password and the software will not accept my entry.
Opaite Mbohovái (2)
You should be able to set it at any time. The help article (Use a Primary Password to protect stored logins and passwords) shows "(not set)" for the current password when first setting it up. When you open that dialog on your Firefox, it behaves as though you already set a password? That's odd... not sure what could cause that. Hopefully someone else will have a suggestion that doesn't involve losing your existing passwords.
See http://kb.mozillazine.org/Master_password
You haven't enabled FIPS mode by any chance?
- Tools > Options > Advanced : Encryption: Security Devices
- https://support.mozilla.org/kb/Configuring+Firefox+for+FIPS+140-2
If you have then the only way to recover is to delete the signons.sqlite and key3.db files in the Firefox profile folder.