Gitlab Backup and "Unable to to verify certificate"

In our Ubuntu server, an ex-partner has installed our Gitlab. I have no experience with gitlab. Now, I want to create a backup.

After running

sudo gitlab-rake gitlab:backup:create

I get the following error:

Uploading backup archive to remote storage smartupgitlab ... rake aborted! Excon::Errors::SocketError: Unable to verify certificate, please set Excon.defaults[:ssl_ca_path] = path_to_certs, ENV['SSL_CERT_DIR'] = path_to_certs, Excon.defaults[:ssl_ca_file] = path_to_file, ENV['SSL_CERT_FILE'] = path_to_file, Excon.defaults[:ssl_verify_callback] = callback (see OpenSSL::SSL::SSLContext#verify_callback), or Excon.defaults[:ssl_verify_peer] = false (less secure).

I guess I must use the indicated lines of code, but in what file exactly should I paste them?

Backup upload to a remote location is configured on your installation. The location specified doesn't exist however. Commenting out gitlab_rails['backup_path'] and gitlab_rails['backup_upload_connection'] should make it work again. Once commented out run gitlab-ctl reconfigure and local backups should work again.