GeoIP2-php: cURL error (77): error setting certificate verify locations:

Lately, I’ve been getting this error: Uncaught MaxMind\Exception\HttpException: cURL error (77): error setting certificate verify locations:

I’ve tried downloading certs from http://curl.haxx.se/ca/cacert.pem and installing them on my Ubuntu 16.04 system in /etc/ssl/certs, but it does not fix the problem.

I’ve also tried setting curl.cainfo="/etc/ssl/certs/cacert.pem" in my php.ini and that makes no difference.

If I edit the MaxMind\Webservice\Http\CurlRequest.php file and set CURLOPT_SSL_VERIFYPEER to false, it starts working again. However, this is not the best solution.