Host 'your-mysql-server' is blocked because of many connection errors; unblock with 'mysqladmin flush-hosts'
This is error from your MySQL database server that the server is blocked temporarily.
The server is not accepting connections. You have to contact your hosting support with the error message. They will be able to unblock your mysql server. After the MySQL server is ready back again, try re-uploading the form.
If you need further help, submit this form.