CRA Result Code: 35 - filing for a deceased person

Hi - I'm trying to file for my father's estate.  This isn't the Death filing, this is just his filing for 2024.  I get the CRA Result Code: 35 that won't let me netfile.  I've cleared cache, restarted, I'm using Chrome.  Perhaps if you're filing for a deceased person you can't use netfile?  CRA is uncontactable right now (All agents are busy, call back later).