C#反序列化XML文件报错：‘XML文档(1,2)存在错误’的排查

尝试反序列化接口返回的XML响应，已使用Visual Studio的「选择性粘贴」功能生成对应实体类，仅将一个私有字段改为公共字段以在代码中访问（未修改代码片段内的内容）。但反序列化时出现如下错误：

错误信息 #

System.InvalidOperationException: 'There is an error in XML document (1, 2).'
Inner Exception
InvalidOperationException: <Envelope xmlns='http://schemas.xmlsoap.org/soap/envelope/'> was not expected.

实体类Envelope的起始代码 #

[System.SerializableAttribute()]
[System.ComponentModel.DesignerCategoryAttribute("code")]
[System.Xml.Serialization.XmlTypeAttribute(AnonymousType = true, Namespace = "http://schemas.xmlsoap.org/soap/envelope/")]
[System.Xml.Serialization.XmlRootAttribute(Namespace = "http://schemas.xmlsoap.org/soap/envelope/", IsNullable = false)]
public partial class Envelope
{
    private object headerField;
    private EnvelopeBody bodyField;

    /// <remarks/>
    public object Header
    {
        get { return this.headerField; }
        set { this.headerField = value; }
    }

    /// <remarks/>
    public EnvelopeBody Body
    {
        get { return this.bodyField; }
        set { this.bodyField = value; }
    }
}

待反序列化的XML起始内容 #

<SOAP:Envelope xmlns:SOAP='http://schemas.xmlsoap.org/soap/envelope/'>
    <SOAP:Header/>
    <SOAP:Body xmlns:wsu='http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd' xmlns:urn='urn:oio:medarbejder:1.0.0' xmlns:urn1='urn:oio:sagdok:3.0.0'>
        <ns0:ListOutput xmlns:ns0='urn:oio:medarbejder:1.0.0'>
            <!-- 省略内部内容 -->
        </ns0:ListOutput>
    </SOAP:Body>
</SOAP:Envelope>

曾尝试为[System.Xml.Serialization.XmlRootAttribute]添加ElementName属性，但仍出现相同错误。请问遗漏了什么？

核心问题是实体类的Header和Body属性未指定SOAP命名空间，而XML中的<SOAP:Header>和<SOAP:Body>节点属于http://schemas.xmlsoap.org/soap/envelope/命名空间，序列化器无法匹配节点，导致报错。

步骤1：修正Envelope类的属性特性 #

给Header和Body属性添加XmlElement特性，明确指定命名空间：

[System.SerializableAttribute()]
[System.ComponentModel.DesignerCategoryAttribute("code")]
[System.Xml.Serialization.XmlTypeAttribute(AnonymousType = true, Namespace = "http://schemas.xmlsoap.org/soap/envelope/")]
[System.Xml.Serialization.XmlRootAttribute(Namespace = "http://schemas.xmlsoap.org/soap/envelope/", IsNullable = false)]
public partial class Envelope
{
    private object headerField;
    private EnvelopeBody bodyField;

    /// <remarks/>
    [System.Xml.Serialization.XmlElementAttribute(Namespace = "http://schemas.xmlsoap.org/soap/envelope/")]
    public object Header
    {
        get { return this.headerField; }
        set { this.headerField = value; }
    }

    /// <remarks/>
    [System.Xml.Serialization.XmlElementAttribute(Namespace = "http://schemas.xmlsoap.org/soap/envelope/")]
    public EnvelopeBody Body
    {
        get { return this.bodyField; }
        set { this.bodyField = value; }
    }
}

步骤2：验证EnvelopeBody及嵌套类的命名空间 #

确保EnvelopeBody类及其内部嵌套的所有实体类（比如ListOutput、LaesResultat等）的XML特性与XML中的对应节点命名空间完全匹配。例如ListOutput节点属于urn:oio:medarbejder:1.0.0命名空间，对应的类需要添加XmlRoot或XmlElement特性指定该命名空间。

步骤3：正确编写反序列化代码 #

使用XmlSerializer时，确保传入正确的类型，示例代码如下：

using (var reader = new StringReader(xmlContent))
{
    var serializer = new XmlSerializer(typeof(Envelope));
    var envelope = (Envelope)serializer.Deserialize(reader);
}

如果XML包含命名空间前缀映射，无需额外处理前缀，序列化器会自动识别命名空间的实际URI。

内容的提问来源于stack exchange，提问作者Kiesp