For several months I’ve had to suffer with a nasty bug in Trixie’s (Debian 13) net installer.
About the final step of the installation, and as the packages are ready to be downloaded and installed, an error message greets the admin: Error “Mirror does not support the specified release (Trixie)”.
Of course, trying with different mirrors doesn’t help.
A web search reveals that many people are asking about this error, and not getting a useful answer.
This error seems to happen when the system is connected to an IPv6-only network.The DHCP client bundled with the installer (udhcpc6) manages to get an IPv6 reservation, however, it seems the installer fails to actually assign this IP to the network interface. Eventually, the system is left without connectivity to the public internet, and it thinks the mirror has failed, producing the error: “mirror does not support the specified release”.
There’s a bug being tracked about this: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1072526 from June 2024.
Unfortunately the fix is not yet merged into the stable version: https://salsa.debian.org/installer-team/netcfg/-/merge_requests/18
The solution, for now, is to either use an IPv4 network, or configure the IPv6 connection manually, in the console, using the ip command. Modern LLMs should be helpful for crafting such commands.