i have similar problems updating a multiserver setup.
In mysql.log i see that the update script is querying the local db of the master server. The last entries in /var/log/mysql/mysql.log before the script stops with "Unable to read server configuration from database." is:
199 Query SELECT * FROM dbispconfig.server WHERE server_id = 1
I'm using 18.104.22.168 version of ICPConfig.
What else can i check?
Since all service are running fine on the dedicated web and ftp, mail and database server, i assume the mysql connections and privileges are all fine.