I access one TLS URL that's secured by user certificate. I had no problem importing the .p12 certificate into my profile's user certificate store ("Your Certificates"), and I could access the URL. On the TLS URL system, for an unrelated reason, I had to generate a new certificate. My task was to remove the user certificate from my profile's certificate store, and replace with the new certificate. The replacement was perfect: Delete the old certificate, import the new certificate. Enter the cert password, and see the new certificate, with its new serial ID listed in Firefox's certificate store. When I try to visit the TLS secured URL, Firefox gives "Secure Connection Failed" and "SEC_ERROR_BAD_SIGNATURE". It says "Peer has an invalid signature." I'm at a loss how to proceed troubleshooting this.