I am still learning postgres and databases in general, so maybe my problem is some simple knowledge gap. I do not find anything with the same conditions with google, all I find for this error message is dealing with missing privileges and I checked for them several times.
So the problem is that no data can be imported into the database via pgAdmin4, if I am logged in with a user as admin. The group admin has all permissions to all objects on all levels (db, schema, tables also all default privileges) without exception and even is member of postgres. The owner of all objects is postgres. The error message "No permission to relation” does not really make sense to me, as all other manipulations are no issue. Nevertheless, no file can be imported via the pgAdmin4 context menu Import/Export-Dialog. Only if the privilege INSERT is granted directly to the user (or PUBLIC) the import works. The privileges of the group admin are not sufficient.
Via the pgAdmin3 import dialog it works as user/admin and it also works with its psql command line plugin. Therefore, I assume that it is not due to missing privileges, but to pgAdmin4? For some reason it seems to ignore the INSERT privilege of the group during import. This does not apply to any other privilege.
My current workaround is a special import user which has (only) the necessary privileges to import the tables granted directly. I am running PostgreSQL 11.1 on a server and locally I am working on a Windows 7 PC and pgAdmin4.4 .
I am thankful for advice and explanation what I might miss here.
Best, Nanina