I'm very surprised that there is no more output than you show before it actually crashes.  Can you try an Appimage version?  (https://kmymoney.org/appimage.html) or possibly even Flatpak or Snap?  If any of them run, then I suspect either a packaging issue or a problem with one of the underlying libraries.  (I assume you are using the siduction provided package - presumably as a .deb file.)  Another option would be to run under a debugger, such as gdb, to get a backtrace.  For now, you haven't provided enough information to even make much of a guess as to what is wrong.

(In reply to Jack from comment #1)
> I'm very surprised that there is no more output than you show before it
> actually crashes.  Can you try an Appimage version? 
> (https://kmymoney.org/appimage.html) 

That actually works fine (stable version) and does not crash.
It produces a lot of output in Konsole during start.
The first WebConnect related lines of that output are same as with starting kmymoney from the *.deb-package installed in siduction, until the lines "KCrash" show up.

gdb kmymoney returns this:

Reading symbols from kmymoney...
(No debugging symbols found in kmymoney)
(gdb) run
Starting program: /usr/bin/kmymoney
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[New Thread 0x7fffe61ff6c0 (LWP 132954)]
[New Thread 0x7fffdd7ff6c0 (LWP 132955)]
[New Thread 0x7fffe56b76c0 (LWP 132956)]
[New Thread 0x7fffe4eb66c0 (LWP 132957)]
[New Thread 0x7fffde3ff6c0 (LWP 132958)]
[New Thread 0x7fffdcffe6c0 (LWP 132959)]
[New Thread 0x7fffcd5ff6c0 (LWP 132960)]
[New Thread 0x7fffccdfe6c0 (LWP 132961)]
[New Thread 0x7fffb7fff6c0 (LWP 132962)]
[New Thread 0x7fffb77fe6c0 (LWP 132963)]
[New Thread 0x7fffb6ffd6c0 (LWP 132964)]
[New Thread 0x7fffb67fc6c0 (LWP 132965)]
[New Thread 0x7fffb5ffb6c0 (LWP 132966)]
[New Thread 0x7fffb57fa6c0 (LWP 132967)]
[New Thread 0x7fffb4ff96c0 (LWP 132968)]
[New Thread 0x7fff9bfff6c0 (LWP 132969)]
WebConnect: Try to connect to WebConnect server
WebConnect: Connect to server failed
WebConnect: Starting server failed. Try to remove stale socket.
WebConnect: Running in server mode

Thread 1 "kmymoney" received signal SIGSEGV, Segmentation fault.
0x00007ffff58e4153 in sqlcipher_find_db_index () from /lib/x86_64-linux-gnu/libsqlcipher.so.2
(gdb)

Starting debugger gdb --init-eval-command=set auto-solib-add off -nw -n -batch --init-eval-command=set debuginfod enabled on -x /tmp/drkonqi.kdsUlR -x /tmp/drkonqi.eiwZqM -p 155200 /usr/bin/kmymoney
[New LWP 155216]
[New LWP 155215]
[New LWP 155214]
[New LWP 155213]
[New LWP 155212]
[New LWP 155211]
[New LWP 155210]
[New LWP 155209]
[New LWP 155208]
[New LWP 155207]
[New LWP 155206]
[New LWP 155205]
[New LWP 155204]
[New LWP 155203]
[New LWP 155202]
[New LWP 155201]
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
__syscall_cancel_arch () at ../sysdeps/unix/sysv/linux/x86_64/syscall_cancel.S:56

warning: 56	../sysdeps/unix/sysv/linux/x86_64/syscall_cancel.S: No such file or directory
Traceback (most recent call last):
  File "/usr/share/drkonqi/gdb/python/gdb_preamble/preamble.py", line 608, in print_preamble
    print_preamble_internal()
    ~~~~~~~~~~~~~~~~~~~~~~~^^
  File "/usr/share/drkonqi/gdb/python/gdb_preamble/preamble.py", line 582, in print_preamble_internal
    resolve_modules()
    ~~~~~~~~~~~~~~~^^
  File "/usr/share/drkonqi/gdb/python/gdb_preamble/preamble.py", line 565, in resolve_modules
    raise RuntimeError("No corefile found. Cannot resolve modules.")
RuntimeError: No corefile found. Cannot resolve modules.
No corefile found. Cannot resolve modules.
A debugging session is active.

	Inferior 1 [process 155200] will be detached.

Quit anyway? (y or n) [answered Y; input not from terminal]
[Inferior 1 (process 155200) detached]
Sentry is attempting to send 2 pending events
Waiting up to 30 seconds
Press Ctrl-C to quit
Debugging ended with exit code '1' and exit status 'NormalExit'
Debugging ended with exit code '9' and exit status 'CrashExit'

First. after the crash, type "bt" to gdb to get a backtrace.
Where is your data - what type of file?  If you really are using sqlcipher, can you open the data file using sqlcipher directly?  If you are not using it, I'll have to dig where KMyMoney calls it before needing to use it.  However, I really still don't understand why the console output is not more voluminous - such as info about loading plugins.

(In reply to Jack from comment #5)
> First. after the crash, type "bt" to gdb to get a backtrace.
> Where is your data - what type of file?  If you really are using sqlcipher,
> can you open the data file using sqlcipher directly?  If you are not using
> it, I'll have to dig where KMyMoney calls it before needing to use it. 
> However, I really still don't understand why the console output is not more
> voluminous - such as info about loading plugins.

(gdb) bt
#0  0x00007ffff58e4153 in sqlcipher_find_db_index () from /lib/x86_64-linux-gnu/libsqlcipher.so.2
#1  0x00007ffff58e7c8d in sqlite3_key_v2 () from /lib/x86_64-linux-gnu/libsqlcipher.so.2
#2  0x000055555564638c in ?? ()
#3  0x000055555562dcc1 in ?? ()
#4  0x00007ffff5233ca8 in __libc_start_call_main (main=main@entry=0x55555562cdd0, argc=argc@entry=1, argv=argv@entry=0x7fffffffdb38)
    at ../sysdeps/nptl/libc_start_call_main.h:58
#5  0x00007ffff5233d65 in __libc_start_main_impl (main=0x55555562cdd0, argc=1, argv=0x7fffffffdb38, init=<optimized out>, fini=<optimized out>,
    rtld_fini=<optimized out>, stack_end=0x7fffffffdb28) at ../csu/libc-start.c:360
#6  0x000055555562e5a1 in ?? ()
(gdb) QSocketNotifier: Invalid socket 17 and type 'Read', disabling...

I have not decided on which data base to use. It is first time ever I have tried using kmymoney, so I have not set up anything related to sql data base or other. So I do not know "what is my data" nor "what type of file".

Well, the error does seem to be within the sqlite/sqlcipher code.  We should first try to confirm whether KMyMoney works without invoking that code.
When you start the program, are you just running "kmymoney" without any command line arguments?  i have not yet looked into the code, although I don't know why it would be doing so without needing it to read or save your data.  From your description, it sounds like it is crashing immediately on startup, before you go through the process of creating a new data file.   Just for a quick test, does it also crash if you invoke as "kmymoney -n" which tells it not to open any data file on startup (it normally opens whatever data file was last used.)

(In reply to Jack from comment #7)
> Just for a quick test, does it also crash if you invoke as "kmymoney -n"
> which tells it not to open any data file on startup (it normally opens
> whatever data file was last used.)

Same behaviour as before, no change.
I have used command "kmymoney" without arguments so far, adding -n makes no change. Also no change with this command in gdb bt.

Very strange. I thought, sqlcipher is only used by the SQL plugin, but apparently this is not the case:
> /home/thb/devel/kmymoney/build  (master)$ ldd bin/kmymoney | grep sql
>        libsqlcipher-3.41.2.so.0 => /usr/lib64/libsqlcipher-3.41.2.so.0 (0x00007f67ea70d000)
So there is a reference to libsqlcipher somewhere in the code. But since it is working for most people, I could imagine the problem is introduced by the downstream (siduction) build and packaging process. This statement is seconded by the fact, that the AppImage version is working for the OP.

https://invent.kde.org/office/kmymoney/-/blob/master/kmymoney/kmymoney.cpp#L1028-1046 explains why.