This error message has cropped up several times before:
- fedora-38 template fails to download · Issue #8607 · QubesOS/qubes-issues · GitHub
- qvm-template fails to handle repositories with no metalink · Issue #8299 · QubesOS/qubes-issues · GitHub
- Debian 12 templates available - #5 by tanky0u
- Fedora 38 templates available - #2 by quantum
- [qubes-users] Error installing Debian-12 template
You could try this workaround, but I don’t know whether it’ll work in this case:
Also, please feel free to open a bug report for this.
(@marmarek: This seems to be a recurring problem.)