mysqlcheck: Got error: 1698: Access denied for user 'root'@'localhost' when trying to connect

Wanted to update ISPConfig in a multi-server setup, got error on my db-server.
Setup:
Host-1: ISPConfig Master
DB: Database Server
Got error on starting ispconfig_update.sh after giving passwort for master-server password.
Run mysql test on Cli for user root for masterserver (IP and Hostname), Connection Successfull
Run mysql test for root on localhost, Connection successfull
Run mysql test for ispconfig user on localhost, Connection successfull
Log:

Code:

Checking MariaDB version 10.11.13 .. OK
MySQL master server hostname [###]:
MySQL master server port [3306]:
MySQL master server root username [root]:
MySQL master server root password []: ######
MySQL master server database name [dbispconfig]:

Checking ISPConfig database .. mysqlcheck: Got error: 1698: Access denied for user 'root'@'localhost' when trying to connect
OK
ERROR 1698 (28000): Access denied for user 'root'@'localhost'
Unable to call mysql command line with credentials from mysql_clientdb.conf

 

it is, and the error still exists