I'm trying to connect to a website which uses a self-signed certificate. Firefox tells me that my connection is not secure and on clicking Advanced button I can find Add Exception... button, clicking which I get a dialog, where I can confirm the security exception. But the checkbox Permanently store this exception is grayed out, so I'm unable to store it permanently.
How do I fix this?
The option which disables the ability to store security exceptions appears to be Never remember history. You can find it in Options->Privacy->History. Once you switch it to Remember history and restart Firefox, you can permanently store the security exception. If you then switch that option back, the exception will remain stored, so you can enable this feature back after adding the exception.
Confirmed answer from @sdanna. I had to allow "Remember History" temporarily, set the permanent checkbox on my desired site exceptions one by one and then switch it back to "Use Custom Settings." Worked perfectly after that.
