When attempting to log in Unified Self Service (USS) with username that have multi-byte characters or non-English characters the login fails, the login page shows the error bellow:
Your request failed to complete.
Authentication failed. Please try again.
The log files will show no error messages.
The variable 'bypass.liferay.screenname.validation' present in portal-ext.properties is set to "false" by default, this is part of Liferay's (framework on which USS is built), the screenName validation happens and Liferay doesn't support multibyte characters and non-English characters in the screenNames and therefore it is impossible to log in USS or to create users within using this kind of characters.
If this value is set to "true", it allows the authentication without this framework and will allow the use of multibyte characters and non-English characters.
1. Locate the file portal-ext.properties which is under the folder ../CA/Self Service/ OSOP
2. Find and set the variable 'bypass.liferay.screenname.validation' from "false" to "true" and then restart the USS services.