我们有一个运行Symfony 2.0.17版本的站点（是的，我们知道它已经过时，正在迁移到 2.2.x）。它一直运行良好，直到几天前，我们开始收到错误 500并显示此消息：
警告：DOMDocument::schemaValidate()：/var/www/customers/customername/symfony/vendor/symfony/src/Symfony/Component/Validator/Mapping/Loader/XmlFileLoader.php 第 197 行中的架构无效
当我们尝试使用FormBuilder. 在我们的开发和测试环境中一切正常，这使得排除故障非常痛苦。
这个问题的可能原因是什么？自 1 月以来，没有对网站进行任何新的更改，而且它肯定在 3 月初有效，因为这是最新发布内容的时间戳。
这是完整堆栈跟踪的相关部分。DOMDocument->schemaValidate()是导致警告的方法。
at DOMDocument ->schemaValidate ('/var/www/customers/customername/symfony/vendor/symfony/src/Symfony/Component/Validator/Mapping/Loader/schema/dic/constraint-mapping/constraint-mapping-1.0.xsd')
in /var/www/customers/customername/symfony/vendor/symfony/src/Symfony/Component/Validator/Mapping/Loader/XmlFileLoader.php at line 197
at XmlFileLoader ->parseFile ('/var/www/customers/customername/symfony/vendor/symfony/src/Symfony/Component/Form/Resources/config/validation.xml')
in /var/www/customers/customername/symfony/vendor/symfony/src/Symfony/Component/Validator/Mapping/Loader/XmlFileLoader.php at line 32
at XmlFileLoader ->loadClassMetadata (object(ClassMetadata))
in /var/www/customers/customername/symfony/vendor/symfony/src/Symfony/Component/Validator/Mapping/Loader/LoaderChain.php at line 57
at LoaderChain ->loadClassMetadata (object(ClassMetadata))
in /var/www/customers/customername/symfony/vendor/symfony/src/Symfony/Component/Validator/Mapping/Loader/LoaderChain.php at line 57
at LoaderChain ->loadClassMetadata (object(ClassMetadata))
in /var/www/customers/customername/symfony/vendor/symfony/src/Symfony/Component/Validator/Mapping/ClassMetadataFactory.php at line 68
at ClassMetadataFactory ->getClassMetadata ('OurCompany\OurCMSBundle\SearchableInterface')
in /var/www/customers/customername/symfony/vendor/symfony/src/Symfony/Component/Validator/Mapping/ClassMetadataFactory.php at line 65
at ClassMetadataFactory ->getClassMetadata ('OurCompany\OurCMSBundle\Entity\News')
in /var/www/customers/customername/symfony/vendor/symfony/src/Symfony/Component/Form/Extension/Validator/ValidatorTypeGuesser.php at line 314
at ValidatorTypeGuesser ->guess ('OurCompany\OurCMSBundle\Entity\News', 'title', object(Closure))
in /var/www/customers/customername/symfony/vendor/symfony/src/Symfony/Component/Form/Extension/Validator/ValidatorTypeGuesser.php at line 39
at ValidatorTypeGuesser ->guessType ('OurCompany\OurCMSBundle\Entity\News', 'title')
in /var/www/customers/customername/symfony/vendor/symfony/src/Symfony/Component/Form/FormTypeGuesserChain.php at line 46
at Symfony\Component\Form\{closure} (object(ValidatorTypeGuesser))
in /var/www/customers/customername/symfony/vendor/symfony/src/Symfony/Component/Form/FormTypeGuesserChain.php at line 85
at FormTypeGuesserChain ->guess (object(Closure))
in /var/www/customers/customername/symfony/vendor/symfony/src/Symfony/Component/Form/FormTypeGuesserChain.php at line 47
at FormTypeGuesserChain ->guessType ('OurCompany\OurCMSBundle\Entity\News', 'title')
in /var/www/customers/customername/symfony/vendor/symfony/src/Symfony/Component/Form/FormFactory.php at line 315
at FormFactory ->createBuilderForProperty ('OurCompany\OurCMSBundle\Entity\News', 'title', null, array())
in /var/www/customers/customername/symfony/vendor/symfony/src/Symfony/Component/Form/FormBuilder.php at line 575
at FormBuilder ->create ('title', null, array())
in /var/www/customers/customername/symfony/vendor/symfony/src/Symfony/Component/Form/FormBuilder.php at line 691
at FormBuilder ->buildChildren ()
in /var/www/customers/customername/symfony/vendor/symfony/src/Symfony/Component/Form/FormBuilder.php at line 654
at FormBuilder ->getForm ()
in /var/www/customers/customername/symfony/vendor/symfony/src/Symfony/Component/Form/FormFactory.php at line 138
at FormFactory ->create (object(NewsType), object(News), array())
in /var/www/customers/customername/symfony/vendor/symfony/src/Symfony/Bundle/FrameworkBundle/Controller/Controller.php at line 129
at Controller ->createForm (object(NewsType), object(News))
in /var/www/customers/customername/symfony/src/Customer/OurCMSBundle/Controller/NewsController.php at line 127
at NewsController ->editAction ('2')
使用的模式是 Symfony Validator 组件的一部分，位于vendor/symfony/src/Symfony/Component/Validator/Mapping/Loader/schema/dic/constraint-mapping/constraint-mapping-1.0.xsd. 它在使用w3.org 验证器检查时进行验证。这是架构：
<?xml version="1.0" ?>
<xsd:schema xmlns="http://symfony.com/schema/dic/constraint-mapping"
xmlns:xsd="http://www.w3.org/2001/XMLSchema"
targetNamespace="http://symfony.com/schema/dic/constraint-mapping"
elementFormDefault="qualified">
<xsd:annotation>
<xsd:documentation><![CDATA[
Symfony Validator Constraint Mapping Schema, version 1.0
Authors: Bernhard Schussek
A constraint mapping connects classes, properties and getters with
validation constraints.
]]></xsd:documentation>
</xsd:annotation>
<xsd:element name="constraint-mapping" type="constraint-mapping" />
<xsd:complexType name="constraint-mapping">
<xsd:annotation>
<xsd:documentation><![CDATA[
The root element of the constraint mapping definition.
]]></xsd:documentation>
</xsd:annotation>
<xsd:sequence>
<xsd:element name="namespace" type="namespace" minOccurs="0" maxOccurs="unbounded" />
<xsd:element name="class" type="class" maxOccurs="unbounded" />
</xsd:sequence>
</xsd:complexType>
<xsd:complexType name="namespace">
<xsd:annotation>
<xsd:documentation><![CDATA[
Contains the abbreviation for a namespace.
]]></xsd:documentation>
</xsd:annotation>
<xsd:simpleContent>
<xsd:extension base="xsd:string">
<xsd:attribute name="prefix" type="xsd:string" use="required" />
</xsd:extension>
</xsd:simpleContent>
</xsd:complexType>
<xsd:complexType name="class">
<xsd:annotation>
<xsd:documentation><![CDATA[
Contains constraints for a single class.
Nested elements may be class constraints, property and/or getter
definitions.
]]></xsd:documentation>
</xsd:annotation>
<xsd:choice minOccurs="0" maxOccurs="unbounded">
<xsd:element name="group-sequence" type="group-sequence" minOccurs="0" maxOccurs="1" />
<xsd:element name="constraint" type="constraint" minOccurs="0" maxOccurs="unbounded" />
<xsd:element name="property" type="property" minOccurs="0" maxOccurs="unbounded" />
<xsd:element name="getter" type="getter" minOccurs="0" maxOccurs="unbounded" />
</xsd:choice>
<xsd:attribute name="name" type="xsd:string" use="required" />
</xsd:complexType>
<xsd:complexType name="group-sequence">
<xsd:annotation>
<xsd:documentation><![CDATA[
Contains the group sequence of a class. Each group should be written
into a "value" tag.
]]></xsd:documentation>
</xsd:annotation>
<xsd:sequence>
<xsd:element name="value" type="value" minOccurs="1" maxOccurs="unbounded" />
</xsd:sequence>
</xsd:complexType>
<xsd:complexType name="property">
<xsd:annotation>
<xsd:documentation><![CDATA[
Contains constraints for a single property. The name of the property
should be given in the "name" option.
]]></xsd:documentation>
</xsd:annotation>
<xsd:sequence>
<xsd:element name="constraint" type="constraint" maxOccurs="unbounded" />
</xsd:sequence>
<xsd:attribute name="name" type="xsd:string" use="required" />
</xsd:complexType>
<xsd:complexType name="getter">
<xsd:annotation>
<xsd:documentation><![CDATA[
Contains constraints for a getter method. The name of the corresponding
property should be given in the "property" option.
]]></xsd:documentation>
</xsd:annotation>
<xsd:sequence>
<xsd:element name="constraint" type="constraint" maxOccurs="unbounded" />
</xsd:sequence>
<xsd:attribute name="property" type="xsd:string" use="required" />
</xsd:complexType>
<xsd:complexType name="constraint" mixed="true">
<xsd:annotation>
<xsd:documentation><![CDATA[
Contains a constraint definition. The name of the constraint should be
given in the "name" option.
May contain a single value, multiple "constraint" elements,
multiple "value" elements or multiple "option" elements.
]]></xsd:documentation>
</xsd:annotation>
<xsd:choice minOccurs="0">
<xsd:element name="constraint" type="constraint" minOccurs="1" maxOccurs="unbounded" />
<xsd:element name="option" type="option" minOccurs="1" maxOccurs="unbounded" />
<xsd:element name="value" type="value" minOccurs="1" maxOccurs="unbounded" />
</xsd:choice>
<xsd:attribute name="name" type="xsd:string" use="required" />
</xsd:complexType>
<xsd:complexType name="option" mixed="true">
<xsd:annotation>
<xsd:documentation><![CDATA[
Contains a constraint option definition. The name of the option
should be given in the "name" option.
May contain a single value, multiple "value" elements or multiple
"constraint" elements.
]]></xsd:documentation>
</xsd:annotation>
<xsd:choice minOccurs="0">
<xsd:element name="constraint" type="constraint" minOccurs="1" maxOccurs="unbounded" />
<xsd:element name="value" type="value" minOccurs="1" maxOccurs="unbounded" />
</xsd:choice>
<xsd:attribute name="name" type="xsd:string" use="required" />
</xsd:complexType>
<xsd:complexType name="value" mixed="true">
<xsd:annotation>
<xsd:documentation><![CDATA[
A value of an element.
May contain a single value, multiple "value" elements or multiple
"constraint" elements.
]]></xsd:documentation>
</xsd:annotation>
<xsd:choice minOccurs="0">
<xsd:element name="constraint" type="constraint" minOccurs="1" maxOccurs="unbounded" />
<xsd:element name="value" type="value" minOccurs="1" maxOccurs="unbounded" />
</xsd:choice>
<xsd:attribute name="key" type="xsd:string" use="optional" />
</xsd:complexType>
</xsd:schema>