When visiting sites over HTTPS that use a self-signed or expired certificate Firefox will stop dead in it’s tracks with a “This Connection is Untrusted” message. Annoying but necessary given the web-savviness of the majority of net denizens nowadays.
On occasion when clicking “Add Exception…” the option to “permanently store this exception” will be greyed out. Very annoying. Especially when it’s my test server and I created the self-signed cert and I KNOW it’s not valid.
The Solution
The only reliable solution I’ve found is to delete (part of?) Firefox’s certificate database. The file (on Windows 7/Vista) is:
C:\Users\<username>\AppData\Roaming\Mozilla\Firefox\
Profiles\<random-string>.default\cert8.db
Note, you will have to quit FF first. Annoying.
Note to self: try and find a HTTPFox clone for Chrome so I can finally free myself from this awful browser.
You can also turn off private browsing which will un-grey the checkbox, check it and store the certificate, then turn private browsing back on.
@Krontor, man, you are the king! You are the only one who pointed to the right thing. I was never thinking that private browsing would prohibit manual storing of certificates. Many thanks for this, it saved me of infinite searching for solution.