ACMEv1 is fully deprecated and all certificates issued with that version of the API have expired and cannot be renewed using that endpoint. The Let's Encrypt team is continuing to deprecate the service and it is no longer returning an error message.
If you've been attempting to use ACMEv1 your logs would previously include a link to this thread and the included error message:
This thread and many others on the forum can help you upgrade your clients to use ACMEv2 and issue a new certificate.