That’s not from any particular plugin, but from Grafana. It looks like your Grafana can’t reach URL https://grafana.com/api/plugins/ci/keys, where are keys used for plugin signature verification.
Grafana uses semicolons (the ; char) to comment out lines in a .ini file. You must uncomment each line in the custom.ini or the grafana.ini file that you are modify by removing ; from the beginning of that line. Otherwise your changes will be ignored.