This page addresses services and institutions connecting to WAYF through SAML2 without using SimpleSAMLphp. Technical staff there has the option here of downloading metadata containing WAYF's new signing certificate for incorporation into their WAYF setups:

Metadata containing WAYF's new signing certificate

As of the 17th of April at 10 o'clock any entity connecting to WAYF must use the new signing certificate in order for the connection to function. Until then connections can employ metadata holding either the old certificate only, or both the new one and the old one. If your connector system is capable of handling metadata containing multiple alternative certificates, you can download and incorporate immediately metadata comprising both certificates (the old one and the new one), thus getting through the certificate renewal now already. Otherwise, your only option is to download metadata containing the new certificate only, and put it into operation at the above-mentioned time. Until then you will have to use metadata containing the old certificate only, also available for download here, just in case.

Shibboleth 1.3

Services using Shibboleth 1.3 to connect to WAYF may incorporate WAYF's new signing certificate by installing the metadata available here.