Constantly asked for WiFi password and CA certificate

The warning was happening again and again. What I ended up doing was first I did this I clicked the "Choose a Certificate Authority certificate..."

Then I went to "/usr/share/ca-certificates/mozilla/AddTrust_External_Root.crt" and Added that as my certificate.

The certificate error went away but the password prompt for the WiFi did not

So I went to "Edit Connections" and selected my wireless connection.

Then I went to "General" tab and unticked "All users may connect to this network"

No more CA prompt or wireless password prompt.

Some schools and organizations use EAP based authentication without a CA signed certificate, usually because of the costs involved. This warning message is basically the same thing as your web-browser warning about invalid or unsigned SSL certificates for websites. If you trust the certificate used for the connection, you can click the "Don't Warn Me Again" box and then select Ignore and Network Manager should store the credentials for use next time you connect.

I had the dialog popping up, but without removing system-ca-certs I kept getting a failure to connect to the network related to the self-signed certificate. Once I removed the system-ca-certs flag entirely, then I could at least connect to my network using my credentials. So, that was odd. Next, I selected a root cert as someone suggested, and the dialog annoyance went away. I then noticed the system-ca-certs was back, but oddly enough everything connected fine. So, something definitely buggy there, but the way that worked out doesn't make it clear as to what it is.