Saving from a snap (Musescore) no longer possible

snap
1

Hi,

with the latest Musescore (4.6.5, stable), I had been able to save score to various places within my ${HOME} without problems. However, since a few days, this does not work any longer. Regardless where I attempt to save a score, Musescore always displays an error dialog informing me that there had been an error. It’s apparently not related to file or directory permissions as Musescore first writes to a temporary file (ending in .mscz_saving in the same location), and this temporary file is created correctly. Furthermore, the old score file (if any) is removed. Just the final renaming fails. If I rename it manually to something.mscz, I can successfully open the score within Musescore.

I have no idea what might have caused this. Musescore itself had not been updated since my last successful saving of a score. And I did not alter permissions – at least not deliberately. The snap infrastructure might have seen an update, though.

The information (on this problem) in the log is quite sparse:

2026-03-14T19:18:33.821 | INFO | main_thread | NotationProject::makeBackup | Backup won’t be created, file does not exist: /home/ingolf/Dokumente/MuseScore4/Scores/test.mscz 2026-03-14T19:18:33.822 | ERROR | main_thread | ProjectActionsController::saveProjectLocally | [409] An error occurred when copying the file

As stated above, the file /home/ingolf/Dokumente/MuseScore4/Scores/test.mscz_saving is created, though, so it does not look like a general problem related to file/directory access permissions. The content of the file appears to be correct as well.

Any ideas what could have gone wrong here?

Kind regards Ingolf

2

Please try using the snappy-debug utility to check whether there’s related AppArmor violations.

See also: Snappy-debug improvements - doc - snapcraft.io

3

A Note; The musescore snap was not updated in the last few weeks. You could try if reverting core24 will help.

4

Thank you, @Lin-Buo-Ren and @A333 for your suggestions.

Reverting core24 (to the previous version 20260107) unfortunately did not have an impact on the error.

With respect to AppArmor, this is the output of snappy-debug. However, I have no idea how to interpret it…

This is what is output until Musescore is up and running:

INFO: Following '/var/log/syslog'. If have dropped messages, use:
INFO: $ sudo journalctl --output=short --follow --all | sudo snappy-debug
kernel.printk_ratelimit = 0
= AppArmor =
Time: Mar 17 20:54:52
Log: apparmor="DENIED" operation="ptrace" profile="snap.musescore.musescore" pid=9954 comm="mscore" requested_mask="read" denied_mask="read" peer="unconfined"
Ptrace: peer=unconfined (read)
Suggestions:
* add 'system-observe' to 'plugs'
* do nothing if program otherwise works properly

= AppArmor =
Time: Mar 17 20:54:52
Log: apparmor="DENIED" operation="open" profile="snap.musescore.musescore" name="/home/ingolf/.config/QtProject.conf" pid=9954 comm="main" requested_mask="r" denied_mask="r" fsuid=1000 ouid=1000
File: /home/ingolf/.config/QtProject.conf (read)
Suggestions:
* adjust program to read necessary files from $SNAP, $SNAP_DATA, $SNAP_COMMON, $SNAP_USER_DATA or $SNAP_USER_COMMON
* add 'personal-files (see https://forum.snapcraft.io/t/the-personal-files-interface for acceptance criteria)' to 'plugs'

= Seccomp =
Time: Mar 17 20:54:54
Log: auid=1000 uid=1000 gid=1000 ses=3 pid=9954 comm="main" exe="/snap/musescore/240/usr/bin/mscore" sig=0 arch=c000003e 203(sched_setaffinity) compat=0 ip=0x7f2120e076f1 code=0x50000
Syscall: sched_setaffinity
Suggestion:
* ignore the denial if the program otherwise works correctly (unconditional sched_setaffinity is often just noise)

= Seccomp =
Time: Mar 17 20:54:54
Log: auid=1000 uid=1000 gid=1000 ses=3 pid=9954 comm="main" exe="/snap/musescore/240/usr/bin/mscore" sig=0 arch=c000003e 141(setpriority) compat=0 ip=0x7f2120e8165b code=0x50000
Syscall: setpriority
Suggestion:
* ignore the denial if the program otherwise works correctly (unconditional setpriority is often just noise)

And this is the output when I try to save a score:

= AppArmor =
Time: Mar 17 20:56:37
Log: apparmor="DENIED" operation="open" profile="snap.musescore.musescore" name="/proc/9954/mountinfo" pid=9954 comm="gmain" requested_mask="r" denied_mask="r" fsuid=1000 ouid=1000
File: /proc/9954/mountinfo (read)
Suggestions:
* adjust program to not access '@{PROC}/@{pid}/mountinfo'
* add one of 'mount-control, mount-observe, steam-support' to 'plugs'

= AppArmor =
Time: Mar 17 20:56:37
Log: apparmor="DENIED" operation="open" profile="snap.musescore.musescore" name="/etc/fstab" pid=9954 comm="main" requested_mask="r" denied_mask="r" fsuid=1000 ouid=0
File: /etc/fstab (read)
Suggestions:
* adjust program to read necessary files from $SNAP, $SNAP_DATA, $SNAP_COMMON, $SNAP_USER_DATA or $SNAP_USER_COMMON
* adjust snap to use snap layouts (https://forum.snapcraft.io/t/snap-layouts/7207)
* add 'mount-observe' to 'plugs'

= AppArmor =
Time: Mar 17 20:56:37
Log: apparmor="DENIED" operation="open" profile="snap.musescore.musescore" name="/proc/9954/mountinfo" pid=9954 comm="main" requested_mask="r" denied_mask="r" fsuid=1000 ouid=1000
File: /proc/9954/mountinfo (read)
Suggestions:
* adjust program to not access '@{PROC}/@{pid}/mountinfo'
* add one of 'mount-control, mount-observe, steam-support' to 'plugs'

= AppArmor =
Time: Mar 17 20:56:37
Log: apparmor="DENIED" operation="open" profile="snap.musescore.musescore" name="/proc/9954/mounts" pid=9954 comm="main" requested_mask="r" denied_mask="r" fsuid=1000 ouid=1000
File: /proc/9954/mounts (read)
Suggestions:
* adjust program to not access '@{PROC}/@{pid}/mounts'
* add one of 'mount-control, mount-observe, network-control, steam-support' to 'plugs'

= AppArmor =
Time: Mar 17 20:56:38
Log: apparmor="DENIED" operation="open" profile="snap.musescore.musescore" name="/proc/9954/mountinfo" pid=9954 comm="main" requested_mask="r" denied_mask="r" fsuid=1000 ouid=1000
File: /proc/9954/mountinfo (read)
Suggestions:
* adjust program to not access '@{PROC}/@{pid}/mountinfo'
* add one of 'mount-control, mount-observe, steam-support' to 'plugs'

= AppArmor =
Time: Mar 17 20:56:38
Log: apparmor="DENIED" operation="open" profile="snap.musescore.musescore" name="/proc/9954/mounts" pid=9954 comm="main" requested_mask="r" denied_mask="r" fsuid=1000 ouid=1000
File: /proc/9954/mounts (read)
Suggestions:
* adjust program to not access '@{PROC}/@{pid}/mounts'
* add one of 'mount-control, mount-observe, network-control, steam-support' to 'plugs'

= AppArmor =
Time: Mar 17 20:56:38
Log: apparmor="DENIED" operation="dbus_method_call"  bus="system" path="/org/freedesktop/hostname1" interface="org.freedesktop.DBus.Properties" member="GetAll" mask="send" name=":1.133" pid=9954 label="snap.musescore.musescore" peer_pid=10105 peer_label="unconfined"
DBus access
Suggestion:
* try adding 'hostname-control' to 'plugs'

= AppArmor =
Time: Mar 17 20:56:46
Log: apparmor="DENIED" operation="open" profile="snap.musescore.musescore" name="/proc/9954/mountinfo" pid=9954 comm="main" requested_mask="r" denied_mask="r" fsuid=1000 ouid=1000
File: /proc/9954/mountinfo (read)
Suggestions:
* adjust program to not access '@{PROC}/@{pid}/mountinfo'
* add one of 'mount-control, mount-observe, steam-support' to 'plugs'

= AppArmor =
Time: Mar 17 20:56:46
Log: apparmor="DENIED" operation="open" profile="snap.musescore.musescore" name="/proc/9954/mounts" pid=9954 comm="main" requested_mask="r" denied_mask="r" fsuid=1000 ouid=1000
File: /proc/9954/mounts (read)
Suggestions:
* adjust program to not access '@{PROC}/@{pid}/mounts'
* add one of 'mount-control, mount-observe, network-control, steam-support' to 'plugs'

= AppArmor =
Time: Mar 17 20:59:22
Log: apparmor="DENIED" operation="open" profile="system_tor" name="/etc/ssl/openssl.cnf" pid=10149 comm="tor" requested_mask="r" denied_mask="r" fsuid=130 ouid=0
File: /etc/ssl/openssl.cnf (read)
Suggestions:
* adjust program to read necessary files from $SNAP, $SNAP_DATA, $SNAP_COMMON, $SNAP_USER_DATA or $SNAP_USER_COMMON
* adjust snap to use snap layouts (https://forum.snapcraft.io/t/snap-layouts/7207)
* add 'system-files (see https://forum.snapcraft.io/t/the-system-files-interface for acceptance criteria)' to 'plugs'

I did not notice anything explicitly related to the file/directory which I was trying to save the score in. Any further suggestions?

Kind regards Ingolf