XML Schema - XSD is invalid

Error:

I am getting the following error when trying to create an XML schema.

Error Page
Error found while executing request:
Please refer logs for details.
XSD/DTD file selected for upload test.xsd is invalid
due to : SchemaException: Can not get schema: :
javax.xml.bind.UnmarshalException

Cause:

The XSD you are uploading into the create XML schema page is invalid. You can verify this by using an XML tool such as XML Editor.

Generally, there are some special characters or formatting issues that cause the XSD to be invalid. These could be generated by saving the XSD in an unexpected way (copy and paste, view source, etc..).

Solution:

Try copy and pasting the XSD into Notepad (Notepad.exe application shipped with Windows). This removes all formatting automatically.

Save the Notepad file as an XSD. Then upload that file into the XML schema creation page.