Bug#1121934: cdrom: Target install partition fails to mount in EFI installer. Works in non-EFI installer
On 05/12/2025 at 22:02, daan.nusman wrote:
(Always using guided mode, and the entire disk).
* Had a Fedora install with LVM/crypt enabled.
But you overwrote it with Debian, so it does not matter.
* Installed Debian 13.2 with LVM/crypt + full random overwrite, successfully in non-UEFI mode.
This created a /boot partition as #1, with maximum size 1GB, formatted
as ext4.
* Installed Debian 13.2 with LVM/crypt + not a full random overwrite (canceled it): the reported mount fail error occurred here. Suspected the cancel was to blame, so:
This created an EFI partition as #1, with maximum size 1GB. The
installer tries hard (maybe too hard ?) to not reformat EFI partitions,
so if it detects any filesystem in it, then it won't reformat it but
will try to mount it as vfat in any case regardless of the detected
filesystem type.
If the former /boot partition and the new EFI partition had the exact
same position and size, then the installer detected the old ext4
filesystem and did not reformat the partition as FAT. Then it tried and
failed to mount it as vfat.
* Installed Debian 13.2 without LVM: also mount fail.
If the old and new EFI partitions had the same position and size, same
problem as above.
* Installed Debian 13.2 in non-UEFI mode, graphics fix, without LVM. This installed correctly.
This did not create any EFI nor /boot partitions but a big root
partition as #1 formatted as ext4.
* Tried the UEFI mode, no LVM/crypt. This installed correctly.
This created an EFI partition as #1, with maximum size 1GB. The former
root partition #1 had a different size, so its filesystem was not
detected and the new EFI partition was formatted as FAT and could be
successfully mounted as vfat.
* Tried the UEFI mode, LVM/crypt + full bit scramble of the drive. This installed correctly.
This created an EFI partition as #1, with maximum size 1GB. Either the
former and new EFI partitions had the same size and the new one was not
formatted but was already FAT, or they had different sizes and the new
one was formatted as FAT. In any case, it had a FAT filesystem and could
be mounted as vfat.
I cannot be entirely sure about the exact order of events.
If the order is correct then it would explain what happened.
Can you show the current output of "fdisk -l" ?
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