Well you can’t sign new certs (with the current date) with an expired root/intermediate cert, but the root/intermediate cert expiring doesn’t strictly invalidate the already signed certs.
But I was more talking about the end-user certificates in the previous comment.
Recently learned that root CA don’t actually expire. Yes, they have an expiration date, but nothing pays attention to it for a CA.
It depends on the OS. Some do start to warn you about invalid certs for all certs signed by the root CA, but you can often click continue anyway.
Well you can’t sign new certs (with the current date) with an expired root/intermediate cert, but the root/intermediate cert expiring doesn’t strictly invalidate the already signed certs.
But I was more talking about the end-user certificates in the previous comment.