The problem is caused by non-English encoding.
I ran into this problem throughout the entire version 4. The psql command-line tool is also damaged (it spills out incorrect messages instead of error messages).
Fix: open the postgresql.conf file in your database directory. Find and comment on these lines, in my case I had to destroy the Russian language:
#lc_messages = 'Russian_Russia.1251'
If you still want to see localized messages, you can try the sqlectron app , it seems like this is a good backup tool for the clumsy pgAdmin4.
Rabash
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