lubuntu 20.04 qa-test install failed "Command '['btrfs', 'subvolume', 'create', '/tmp/calamares-root-doq1ngjw/@']' returned non-zero exit status 1"

[Chris Guiver]

Lubuntu 20.04 QA-test install on
dell [optiplex] 755 (c2d-e6850, 5gb, amd/ati radeon rv516/x1300/x1550)

testcase: install with an existing partition, (internet, no encryption)
sda9 is used for system, sda8 the home partition; calamares has had issues with this box/setup with the re-use of sda9 before (https://bugs.launchpad.net/ubuntu/+source/calamares/+bug/1864787) however this error 'looks' different on display anyway (could be same issue)

sda9 was last tested as a btrfs install, so I opted for no format & leave it btrfs.

Error on screen is
Command '['btrfs', 'subvolume', 'create', '/tmp/calamares-root-doq1ngjw/@']' returned non-zero exit status 1.
None

Traceback:
File "/usr/lib/x86_64-linux-gnu/calamares/modules/mount/main.py", line 166, in run
    mount_partition(root_mount_point, partition, partitions)

  File "/usr/lib/x86_64-linux-gnu/calamares/modules/mount/main.py", line 94, in mount_partition
    subprocess.check_call(['btrfs', 'subvolume', 'create',

  File "/usr/lib/python3.8/subprocess.py", line 364, in check_call
    raise CalledProcessError(retcode, cmd)

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: calamares 3.2.20-0ubuntu1
ProcVersionSignature: Ubuntu 5.4.0-26.30-generic 5.4.30
Uname: Linux 5.4.0-26-generic x86_64
.etc.calamares.modules.finished.conf:
 ---
 restartNowMode: user-checked
 restartNowCommand: "systemctl -i reboot"
.etc.calamares.modules.partition.conf:
 efiSystemPartition: "/boot/efi"
 enableLuksAutomatedPartitioning: true
 userSwapChoices: none
 drawNestedPartitions: true
 defaultFileSystemType: "ext4"
.etc.calamares.modules.shellprocess_logs.conf:
 ---
 dontChroot: true
 timeout: 30
 script:
     - calamares-logs-helper @@ROOT@@
.etc.calamares.modules.unpackfs.conf:
 ---
 unpack:
     - source: "/cdrom/casper/filesystem.squashfs"
         sourcefs: "squashfs"
         destination: ""
ApportVersion: 2.20.11-0ubuntu27
Architecture: amd64
CasperMD5CheckResult: pass
CasperVersion: 1.445
CurrentDesktop: LXQt
Date: Wed Apr 22 11:16:43 2020
LiveMediaBuild: Lubuntu 20.04 LTS "Focal Fossa" - Release amd64 (20200421)
RelatedPackageVersions:
 calamares-settings-ubuntu-common 1:20.04.2
 calamares-settings-lubuntu 1:20.04.2
 xfsprogs 5.3.0-1ubuntu2
 btrfs-progs 5.4.1-2
SourcePackage: calamares
UpgradeStatus: No upgrade log present (probably fresh install)

[Chris Guiver (guiverc)]

KDE Partition Manager won't open after calamares failure, seg-faulting which I've mentioned before in reports; so I reboot & start again.

Checked BRTFS file system on sda9, it reports no errors, detected with name of "sus_sys" I'd applied (I was expecting Unknown, but it probably didn't format and just re-used)

[Ubuntu QA Website (ubuntuqa)]

This bug has been reported on the Ubuntu ISO testing tracker.

A list of all reports related to this bug can be found here:
http://iso.qa.ubuntu.com/qatracker/reports/bugs/1874168

[Simon Quigley (tsimonq2)]

Focal is EOL etc etc :)