Segmentation fault on startup

Hi,

I'm running a nextcloud server in a docker container on an RasPi 4 (only 
SSD, no SD), which uses PostgreSQL 10 as server.
The containers are started via docker compose. The PostgreSQL service 
looks like

services:
         db:
                 image: postgres:10-alpine
                 restart: always
                 volumes:
                         - nextcloud_db:/var/lib/postgresql/data
                 environment:
                         - POSTGRES_PASSWORD=xxx
                         - POSTGRES_DB=nextcloud
                         - POSTGRES_USER=nextcloud

Anything worked smoothly for some month now.

Today I had to restart the RasPi. Now the container fails to start with 
a segmentation violation.
I tried to start the server manually, I set
    log_min_messages = info
    log_min_error_statement = info
    log_error_verbosity = verbose

But all I get is
waiting for server to start....1970-05-04 03:17:36.010 UTC [31] LOG: 
00000: listening on IPv4 address "0.0.0.0", port 5432
1970-05-04 03:17:36.010 UTC [31] LOCATION:  StreamServerPort, pqcomm.c:590
1970-05-04 03:17:36.010 UTC [31] LOG:  00000: listening on IPv6 address 
"::", port 5432
1970-05-04 03:17:36.010 UTC [31] LOCATION:  StreamServerPort, pqcomm.c:590
1970-05-04 03:17:36.010 UTC [31] LOG:  00000: listening on Unix socket 
"/var/run/postgresql/.s.PGSQL.5432"
1970-05-04 03:17:36.010 UTC [31] LOCATION:  StreamServerPort, pqcomm.c:585
.1970-05-04 03:17:36.010 UTC [31] LOG:  00000: startup process (PID 32) 
was terminated by signal 11: Segmentation fault
1970-05-04 03:17:36.010 UTC [31] LOCATION:  LogChildExit, postmaster.c:3639
1970-05-04 03:17:36.010 UTC [31] LOG:  00000: aborting startup due to 
startup process failure
1970-05-04 03:17:36.010 UTC [31] LOCATION:  reaper, postmaster.c:2893
1970-05-04 03:17:36.010 UTC [31] LOG:  00000: database system is shut down
1970-05-04 03:17:36.010 UTC [31] LOCATION:  UnlinkLockFiles, miscinit.c:764
  stopped waiting
pg_ctl: could not start server
Examine the log output.


Well. I got stuck. I have no idea how I can find out what went wrong let 
alone how to repair my database.
I have a dump of the data, but without running server I can't do 
anything with it either...

Can someone tell me, what I could do?

Thank you.

-- 
Gruß Helmut