[Pkg-owncloud-maintainers] Bug#996924: nextcloud-desktop: deletes dirs on the server although they're still here locally

[Roland Mas]

Package: nextcloud-desktop
Version: 3.1.1-2+deb11u1
Severity: important

>From time to time, whole directories get erased from the server for no
reason.  I've seen it happen a few times already, but not early enough
to be able to catch logs. So far I've been lucky enough to be able to
restore from backups, but it's not something that I can afford to see
happen again.

In my case, the client sent a DELETE request for a directory that
hadn't been deleted locally. The
~/.local/share/Nextcloud/Documents_sync.log file shows it:

12:27:42||TEMP|INST_REMOVE|Up|1633813324|61620350e2e1d|0|06377550ocptyqgkbgt0|4||204|0|0||||

At the same time, the server log shows the corresponding request:

[REDACTED] [17/Oct/2021:14:27:42 +0200] "DELETE /remote.php/dav/files/DetR/Documents/TEMP HTTP/1.1" 204 609 "-" "Mozilla/5.0 (Linux) mirall/3.1.1-2+deb11u1 (Nextcloud)"

So obviously, on all other clients using that shared Documents
directory, the TEMP directory is deleted. It's still present locally,
but there's a discrepancy with the server, and that discrepancy is not
always resolved in the right direction: sometimes in the past the
directory was restored from the local version and eventually
re-uploaded then re-synced to other clients, but other times the local
version was deleted too, in which case the directory is completely
lost.

This is really major, and the fact that it happens "rarely" (although
a couple of times a year for me) doesn't make it less grave.

For reference the server runs 21.0.0, but I've seen this bug happen
with previous versions too, and I don't think the bug is server-side.

I'm fully willing to help provide more info if instructed how, but
note that the bug is unpredictable to me.

It may be relevant that my Documents share is about 500 GB in size,
with about 300k files.

Please advise.

-- System Information:
Debian Release: 11.1
  APT prefers stable-updates
  APT policy: (500, 'stable-updates'), (500, 'stable-security'), (500, 'stable')
Architecture: amd64 (x86_64)

Kernel: Linux 5.10.0-8-amd64 (SMP w/8 CPU threads)
Locale: LANG=fr_FR.UTF-8, LC_CTYPE=fr_FR.UTF-8 (charmap=UTF-8), LANGUAGE not set
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages nextcloud-desktop depends on:
ii  libc6                          2.31-13+deb11u2
ii  libcloudproviders0             0.3.0-3
ii  libgcc-s1                      10.2.1-6
ii  libglib2.0-0                   2.66.8-1
ii  libnextcloudsync0              3.1.1-2+deb11u1
ii  libqt5core5a                   5.15.2+dfsg-9
ii  libqt5dbus5                    5.15.2+dfsg-9
ii  libqt5gui5                     5.15.2+dfsg-9
ii  libqt5keychain1                0.10.0-1
ii  libqt5network5                 5.15.2+dfsg-9
ii  libqt5qml5                     5.15.2+dfsg-6
ii  libqt5quick5                   5.15.2+dfsg-6
ii  libqt5quickcontrols2-5         5.15.2+dfsg-2
ii  libqt5sql5-sqlite              5.15.2+dfsg-9
ii  libqt5svg5                     5.15.2-3
ii  libqt5webenginecore5           5.15.2+dfsg-3
ii  libqt5webenginewidgets5        5.15.2+dfsg-3
ii  libqt5webkit5                  5.212.0~alpha4-11
ii  libqt5widgets5                 5.15.2+dfsg-9
ii  libstdc++6                     10.2.1-6
ii  nextcloud-desktop-common       3.1.1-2+deb11u1
ii  nextcloud-desktop-l10n         3.1.1-2+deb11u1
ii  qml-module-qtgraphicaleffects  5.15.2-2
ii  qml-module-qtqml-models2       5.15.2+dfsg-6
ii  qml-module-qtquick-controls2   5.15.2+dfsg-2
ii  qml-module-qtquick-layouts     5.15.2+dfsg-6
ii  qml-module-qtquick-window2     5.15.2+dfsg-6
ii  qml-module-qtquick2            5.15.2+dfsg-6

Versions of packages nextcloud-desktop recommends:
ii  nextcloud-desktop-doc  3.1.1-2+deb11u1

nextcloud-desktop suggests no packages.

-- no debconf information