We've recently started getting the following error when the using the Laravel / MailChimp library (https://github.com/spatie/laravel-newsletter):
API call to lists/unsubscribe failed: SSL certificate problem: unable to get local issuer certificate
We're running an Ubuntu 14.04 x64 server via Laravel Forge.
As far as I can tell, this error started appearing after we applied the latest OS updates.
How can we fix this issue? If this requires downloading and enabling new certificates, how do we do this (on Ubuntu with PHP/nginx)?
I've just been dealing with this and used William Turrell's answer which worked for me: SSL errors using MailChimp's API