medictruck By no means an expert but I tried
sysupgrade in a virtual machine just today, upgrading from NetBSD 9.1 to 9.2. I installed
I typed in this command as root:
sysupgrade auto http://cdn.netbsd.org/pub/NetBSD/NetBSD-9.2/amd64
http:// rather than
https:// and that uppercase/lowercase must be respected. It initially failed because I'd typed "netbsd" in the url.
Is that how you went about it?