Mysql:unknown variable ' default-collation=utf8_general_ci '

Unable to log in because the default encoding is set in the configuration document

Comment It out and the problem will be solved.

You can't find the line of txt = ' a ' in Utf8_bin, and Utf8_general_ci can.
Utf8_general_ci is not case-sensitive, you should use this when registering your username and mailbox.
Utf8_general_cs case-sensitive, if the user name and mailbox Use this will be bad consequences
Utf8_bin: String Each string is compiled with binary data stored. Case-sensitive and binary content can be stored

Mysql:unknown variable ' default-collation=utf8_general_ci '