1. Why does the connection to our server fail?
The most common cause of failed certificate verification is an outdated Trusted Root Certificate on the client system. If the server certificate verification fails, this may also be due to an outdated TLS implementation or incompatible operating systems, versions, or distributions.
2. Which certificates do we use?
Our server certificates are based on the Sectigo DV TLS Roots (valid from June 2, 2025), specifically:
Sectigo Public Server Authentication Root R46
Link to the certificate
Sectigo provides an overview of the corresponding intermediate and root certificates:
https://www.sectigo.com/faqs/detail/Sectigo-Public-Intermediates-and-Roots
3. How can I fix the problem?
Recommended solution:
Update the system CA certificates on the affected system.
This is the cleanest and most long-term solution, as future certificate changes will be automatically supported.
Alternative solution / workaround:
Manually import the root certificate mentioned above into the existing CA store of the system.
The certificate verification can then also be successfully performed on older systems.
Temporary remedy:
Deactivate the certificate verification on the client side.
This method should only be used temporarily.