The target table user of the INSERT is not insertable-into

[TeHashX]

Hi, when I try to create a new virtual server, I get error:

Creating MySQL login ..
.. MySQL database failed! : mysql::execute_sql_logged failed : SQL insert into user (host, user, ssl_type, ssl_cipher, x509_issuer, x509_subject, plugin, authentication_string) values ('localhost', 'someusername', '', '', '', '', 'mysql_native_password', password('xxxxxxxxxx')) failed : The target table user of the INSERT is not insertable-into at /usr/share/webmin/web-lib-funcs.pl line 1478.

Running MariaDb server v10.4.3 on Debian v9.8