XSD error: No matching global declaration available for the validation root

Question

When I try to validate the XML file I am given this error:

person.xml:3: element person: Schemas validity error : Element {http://www.namespace.org/person}person: No matching global declaration available for the validation root.

This is the content of the person.xml file:

<?xml version="1.0"?>
<p:person xmlns:p="http://www.namespace.org/person">
  <firstName>name</firstName>
  <surName>surname</surName>
  <secondName>n2</secondName>
</p:person>

This is the content of the person.xsd file:

<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
           xmlns:p="http://www.namespace.org/person"   
           version="1.0">

    <xs:element name="person">
        <xs:complexType>
            <xs:group ref="credential"/>
        </xs:complexType>
    </xs:element>

    <xs:group name="credential">
        <xs:sequence>
            <xs:element name="firstName" type="xs:string"/>
            <xs:element name="surName" type="xs:string"/>
            <xs:element name="secondName" type="xs:string"/>
        </xs:sequence>
    </xs:group>     
</xs:schema>

Answer 1

The error indicates that the namespaced element, {http://www.namespace.org/person}person, is not found in the given XSD because the p element there is not in the http://www.namespace.org/person namespace. Correct the problem by adding targetNamespace="http://www.namespace.org/person" to the xs:schema root element of the XSD. Next, adjust the reference to the credential group to also use that namespace.

Altogether, the following XML will be valid against the following XSD:

XML

<?xml version="1.0"?>
<p:person xmlns:p="http://www.namespace.org/person">
  <firstName>name</firstName>
  <surName>surname</surName>
  <secondName>n2</secondName>
</p:person>

XSD

<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" 
  xmlns:p="http://www.namespace.org/person"
  targetNamespace="http://www.namespace.org/person"
  version="1.0">
  
  <xs:element name="person">
    <xs:complexType>
      <xs:group ref="p:credential"/>
    </xs:complexType>
  </xs:element>
  
  <xs:group name="credential">
    <xs:sequence>
      <xs:element name="firstName" type="xs:string"/>
      <xs:element name="surName" type="xs:string"/>
      <xs:element name="secondName" type="xs:string"/>
    </xs:sequence>
  </xs:group>  

</xs:schema>