System:
Ubuntu 22.04
Linux 5.15.0-118-generic #128-Ubuntu

System is behind firewall, but has been configured with working wildcard DNS and cert ;-)

Issue:
Each attempt to take a grain backup ends with this short message above.

Nevertheless there appears a (empty) file under /opt/sandstorm/var/sandstorm/backups/

The log reads as follows, which seems to point at a permission issue during mount -bind ?

Any Ideas?

kj/compat/http.c++:7233: info: threw exception while serving HTTP response; exception = (remote):0: failed: remote exception: expected !isRetry; retry supervisor startup logic failed
stack: 47a6d0 5d7b00 5d8410 416b10 40f5e0 5d8410 6f7fd0 6ef240 4fa150 4fca90
capnp/rpc.c++:160: info: returning failure over rpc; exception = sandstorm/util.c++:67: failed: openat(dirfd, name.cStr(), flags, mode): No such file or directory; name = jwX7TcZQGe33WpFH7iEsJN
stack: 403a17 6a8ecf 6916f9 6a7176 6a723a 5dcf2e 5dde92 47f830
Exception while invoking method 'backupGrain' Error: remote exception: openat(dirfd, name.cStr(), flags, mode): No such file or directory; name = jwX7TcZQGe33WpFH7iEsJN
*** Uncaught exception ***
sandstorm/backup.c++:95: failed: mount(src.cStr(), dst.cStr(), nullptr, MS_BIND | MS_REC | MS_REMOUNT | flags, nullptr): Operation not permitted; src = /dev; dst = /tmp/dev
stack: 761026 761572 762dd2 494340
capnp/rpc.c++:160: info: returning failure over rpc; exception = sandstorm/util.c++:721: failed: expected exitCode == 0 [1 == 0]; child process failed; name = backup; exitCode = 1
stack: 408c01 69bd15 47f830
Exception while invoking method 'backupGrain' Error: remote exception: expected exitCode == 0 [1 == 0]; child process failed; name = backup; exitCode = 1