Certificate expired

Hi,
A leacy application stops with this error:

org.xmlrpc.android.XMLRPCException: javax.net.ssl.SSLHandshakeException: Certificate expired at …

I test this app on my Samsung A72 mobile.
Can you explain where I could find this cert and how I could intall it up, please.
I’m still lame. :flushed:

Sorry, but this question has nothing to do with Gradle, so please take it to some more appropriate place.