Update: From another forum thread I learned that Duplicati writes a stack trace to stdout when started from the command line. I cannot upload .txt files here, but here are the first few lines:
~> /Applications/Duplicati.app/Contents/MacOS/duplicati
Server has started and is listening on 127.0.0.1, port 8200
Stacktrace:
at <unknown> <0xffffffff>
at (wrapper managed-to-native) System.IO.MonoIO.FindFirstFile (string,string&,int&,int&) [0x00000] in <6e9b92f0d119424382ef180639777acb>:0
at System.IO.FileSystemEnumerableIterator`1<TSource_REF>.CommonInit () [0x0001d] in <6e9b92f0d119424382ef180639777acb>:0
at System.IO.FileSystemEnumerableIterator`1<TSource_REF>..ctor (string,string,string,System.IO.SearchOption,System.IO.SearchResultHandler`1<TSource_REF>,bool) [0x000d6] in <6e9b92f0d119424382ef180639777acb>:0
at System.IO.FileSystemEnumerableFactory.CreateFileNameIterator (string,string,string,bool,bool,System.IO.SearchOption,bool) [0x00009] in <6e9b92f0d119424382ef180639777acb>:0
at System.IO.Directory.EnumerateFileSystemNames (string,string,System.IO.SearchOption,bool,bool) [0x00000] in <6e9b92f0d119424382ef180639777acb>:0
at System.IO.Directory.InternalEnumerateFileSystemEntries (string,string,System.IO.SearchOption) [0x00000] in <6e9b92f0d119424382ef180639777acb>:0
at System.IO.Directory.EnumerateFileSystemEntries (string) [0x0000e] in <6e9b92f0d119424382ef180639777acb>:0
at Duplicati.Server.WebServer.RESTMethods.Filesystem/<>c__DisplayClass3_0.<ListFolderAsNodes>b__0 (string) [0x00008] in <670b0e4a9ae144208688fcb192d20146>:0
...
Then a native stacktrace follows:
Native stacktrace:
w32error-unix.c: unknown error (6) "Device not configured"
0 mono-sgen 0x0000000106d6705e mono_handle_native_crash + 242
1 libsystem_platform.dylib 0x00007fff768dbf5a _sigtramp + 26
2 ??? 0x0000000116768558 0x0 + 4671833432
3 libsystem_c.dylib 0x00007fff766791ae abort + 127
4 mono-sgen 0x0000000106ef68e0 mono_log_write_logfile + 351
5 mono-sgen 0x0000000106f0a18b monoeg_g_logv + 83
6 mono-sgen 0x0000000106f0a27e monoeg_g_log + 120
7 mono-sgen 0x0000000106ddad42 mono_w32error_unix_to_win32 + 239
8 mono-sgen 0x0000000106dd4e9d _wapi_set_last_path_error_from_errno + 61
9 mono-sgen 0x0000000106dd5df1 mono_w32file_find_first + 1053
10 mono-sgen 0x0000000106e00c8a ves_icall_System_IO_MonoIO_FindFirstFile + 49
...
After that, some gdb output follows.
Debug info from gdb:
(lldb) command source -s 0 '/tmp/mono-gdb-commands.gUjQC1'
Executing commands in '/tmp/mono-gdb-commands.gUjQC1'.
(lldb) process attach --pid 99620
Process 99620 stopped
* thread #1, name = 'tid_307', queue = 'com.apple.main-thread', stop reason = signal SIGSTOP
frame #0: 0x00007fff76714246 libsystem_kernel.dylib`semaphore_wait_trap + 10
libsystem_kernel.dylib`semaphore_wait_trap:
-> 0x7fff76714246 <+10>: retq
0x7fff76714247 <+11>: nop
libsystem_kernel.dylib`semaphore_wait_signal_trap:
0x7fff76714248 <+0>: movq %rcx, %r10
0x7fff7671424b <+3>: movl $0x1000025, %eax ; imm = 0x1000025
Target 0: (mono-sgen) stopped.
Executable module set to "/usr/local/Cellar/mono/5.4.1.6/bin/mono-sgen".
Architecture set to: x86_64h-apple-macosx.
(lldb) thread list
Process 99620 stopped
...
At the end of the output, this message occurs:
=================================================================
Got a SIGABRT while executing native code. This usually indicates
a fatal error in the mono runtime or one of the native libraries
used by your application.
=================================================================
Shell error code is 134. I am posting this information here in the hope it may help understanding the scenario better.