[FIXED] Fatal: unable to access 'https://gopkg.in/[…]': server certificate verification failed. CAfile: none CRLfile: none

I am trying to get go packages to download from gopkg.in. It works fine on my local machine, but on CircleCI, I get this:

# cd .; git clone -- https://gopkg.in/yaml.v2 /go/src/gopkg.in/yaml.v2
Cloning into '/go/src/gopkg.in/yaml.v2'...
fatal: unable to access 'https://gopkg.in/yaml.v2/': server certificate verification failed. CAfile: none CRLfile: none
package gopkg.in/yaml.v2: exit status 128

This code used to work fine for around 18 months and just stopped working a few days ago.

Could that be a thing? Looks like it could be a thing? Maybe⸮

In case someone else stumbles upon this: update your root CA…

On Debian:

apt-get --allow-releaseinfo-change update && apt upgrade -y