Example of failure:
SQL> connect 192.168.1.105:employee user sysdba password 123;
Statement failed, SQLSTATE = 08001
Invalid connection string
-Cannot transliterate character between character sets
-Invalid or incomplete multibyte or wide character
It happens when a connection is being established from a client host with non-ASCII (e.g. Cyrillic) name or with non-ASCII OS user name. This could be quite common in the Windows world.