[facet 'maxLength'] The value exceeds the allowed length

A value longer (or shorter) than the schema allows.

The message, as the validator reports it

Element 'note': [facet 'maxLength'] The value has a length of '17'; this exceeds the allowed maximum length of '10'.

Why it happens

Free text longer than a field allows: names, addresses, references.
Length is counted in characters, not bytes, after whitespace handling for the type.

How to fix it

Shorten the value to the limit the message gives (or lengthen it for minLength). Truncate deliberately where the data is produced rather than letting another system cut it.

Example

Validated against order.xsd, below.

Reports the error

<order currency="EUR">
  <id>A-1</id>
  <qty>1</qty>
  <note>far too long text</note>
</order>

Fixed

<order currency="EUR">
  <id>A-1</id>
  <qty>1</qty>
  <note>short</note>
</order>

order.xsd

<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema">
  <xs:element name="order">
    <xs:complexType>
      <xs:sequence>
        <xs:element name="id" type="xs:string"/>
        <xs:element name="qty" type="xs:int"/>
        <xs:element name="status" type="Status" minOccurs="0"/>
        <xs:element name="code" type="Code" minOccurs="0"/>
        <xs:element name="note" type="Short" minOccurs="0"/>
      </xs:sequence>
      <xs:attribute name="currency" type="xs:string" use="required"/>
    </xs:complexType>
  </xs:element>
  <xs:simpleType name="Status">
    <xs:restriction base="xs:string">
      <xs:enumeration value="open"/>
      <xs:enumeration value="paid"/>
    </xs:restriction>
  </xs:simpleType>
  <xs:simpleType name="Code">
    <xs:restriction base="xs:string">
      <xs:pattern value="[A-Z]{3}-[0-9]{4}"/>
    </xs:restriction>
  </xs:simpleType>
  <xs:simpleType name="Short">
    <xs:restriction base="xs:string">
      <xs:maxLength value="10"/>
    </xs:restriction>
  </xs:simpleType>
</xs:schema>