Some time this error occur when you run git clone command:
error: server certificate verification failed. CAfile: /etc/ssl/certs/ca-certificates.crt CRLfile: none while accessing https://firstname.lastname@example.org/xxxx/xxxx.git/info/refs
fatal: HTTP request failed
To get rid of from this error you need to run only one following command:
Now you can do git clone and it should work fine.