**The article will be updated when new information arrives**
This error occurred on september 30, when a new and updated SSL certificate was introduced worldwide.
The problem is seen on older webshop with older and not updated servers. These old servers cannot recognize this never and more safe SSL certificate.
New certificate: ISRG Root X1
Old certificate: DST Root CA X3
Article about the new standard: https://letsencrypt.org/docs/dst-root-ca-x3-expiration-september-2021/
You have to update your webshops server to the newest version, which will recognize the new ISRG Root X1 SSL certificate.
Contact Smart Sends support on email@example.com and get one of our developers to create a workaround locally on your webshop.
A developer costs 120€/hour.
We need an admin user access to your webshop, created for firstname.lastname@example.org and a link to where we can login.