Bug#1121934: cdrom: Target install partition fails to mount in EFI installer. Works in non-EFI installer

Daan Nusman <[email protected]> Thu, 04 Dec 2025 22:38:42 +0100
Newsgroups gmane.linux.debian.ports.amd64
Message-ID <176488432209.2645.9751721462483915987.reportbug__17297.0660774567$1764884491$gmane$org@spire.lan>
Package: cdrom
Severity: important
Tags: d-i
X-Debbugs-Cc: [email protected], [email protected], [email protected]
User: [email protected]
Usertags: amd64
User: [email protected]
Usertags: amd64

Dear Maintainer,

I got a system that installs in non-UEFI mode but fails to mount the target install partition in UEFI mode. I've been told by a Linux graphics driver specialist that is bug is worth reporting.

   * What led up to the situation?

Old PC (Intel Core i5-4690K CPU), SecureBoot off, Ventoy-based USB stick with Debian 13.2.0 netinst ISO.

   * What exactly did you do (or not do) that was effective (or ineffective)?

Ineffective: UEFI boot the USB stick, during "Partition Disks" the system says "The attempt to mount a fil system with type vfat in SCSI3 (0,0,0), partition #1 (sda) at /boot/efi failed".

Effective: non-UEFI boot the stick, choose "Graphical Install" (note: I have to remove "vga=788" otherwise the display on the Radeon RX 5550 gets garbled -- I have been told this is a bug in the GPU BIOS), the install completes fine in 80x25 GUI mode.


Kind regards,

Daan