so finally I have a workaround which is ok for me. When I seperate the tables and the data (using the -a and -s switch from pg_dump) into 2 sql backup files, everything works ok on the problem-VM.
I try to investigate further in the coming weeks, I´m on holiday next week.
I have taken a part of the backup SQL file which fills the table
COPY dev_my_settings (.....) from stdin; 12345 text text 0 123.345345
This file ALONE works! (without changing ANYTHING!)
Hmm, almost like the encoding/locale is changing in the complete file.
So if I run the first (huge) SQL file and then the second, which fills the dev_my_settings table, everything is ok.
FYI if you do a pg_dump using the custom format(-Fc) you have more control over the restore. You can run pg_restore -l against the dump file to get a Table of Contents(TOC), which you can edit by commenting out items you do not want to restore and then feed back to pg_restore via -L. You also have the option to 'restore' all or part of the custom file to a text file using the -f option. The details can be found here: