Exactly same problem here. I deleted all entries in that Settings table. Afterwards I had again access to the user interface from plesk. After giving in again the settings for the first client, it did the same problem again.... I also tried it with a different ftp server, and also with a new ftp...
Same problem
I have the same problem. checked and repaired the tables. Rebooted. Nothing. I have installed 10.1.1 version. Also , i was able to log into https://<your host name>:8443/plesk-billing/admin/ .