Why does a PayPal payment fail with the message «SSL certificate problem: unable to get local issuer certificate»?

PayPal NVP CURL connection error #60: SSL certificate problem: unable to get local issuer certificate

https://github.com/magento/magento2/blob/6ce74b2/app/code/Magento/Paypal/Model/Api/Nvp.php#L1180-L1180


https://github.com/magento/magento2/blob/6ce74b2/app/code/Magento/Paypal/Model/AbstractConfig.php#L131-L141


https://github.com/magento/magento2/blob/6ce74b2/app/code/Magento/Paypal/etc/adminhtml/system/express_checkout.xml#L367-L372

So, you can solve the problem by disabling the «PayPal Express Checkout» → «Basic Settings - PayPal Express Checkout» → «Advanced Settings» → «Enable SSL verification» option or «PayPal Website Payments Standard» → «Basic Settings - PayPal Website Payments Standard» → «Advanced Settings» → «Enable SSL verification» option.

A better solution: How to fix the «SSL certificate problem: unable to get local issuer certificate» issue.

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