Incomplete certificate chain

What causes this issue?

The system could not create a complete certificate chain.

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

Either insert a missing root certificate or a missing intermediate
certificate in the certificate database of the Trust Manager or add the
missing certificates to the certificate response. See also SAP Note
508307.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.