IE11出现“__doPostBack未定义”的解决办法。

点击VS的工具菜单--》库程序包管理器--》程序包管理器控制台（如果没有“库程序包管理器”的菜单，就先点那个“扩展管理器”，安装一个叫“NuGet程序包管理器”，然后就会有了。），点击后下面会出现一个连接PowerShell的控制台，等控制台加载完毕后输入

install-package App_BrowsersUpdate 回车

等待安装完成后，网站根目录下面会出现一个App_BrowsersUpdate目录。​

然后再访问就不会出现“__doPostBack未定义”的错误提示了。

使用VS2010的话，根目录会出现App_Browsers这个目录，如果使用IE11的还是会出现“__doPostBack未定义”的错误提示了。

打开App_Browsers=》ie.browser=》​

加上如下这段代码：​

<browser id="IE11" parentID="Mozilla">
      <identification>
        <userAgent match="Trident\/7.0; rv:(?'version'(?'major'\d+)(\.(?'minor'\d+)?)(?'letters'\w*))(?'extra'[^)]*)" />
        <userAgent nonMatch="IEMobile" />
      </identification>
      <capture>
        <userAgent match="Trident/(?'layoutVersion'\d+)" />
      </capture>
      <capabilities>
        <capability name="browser" value="IE" />
        <capability name="layoutEngine" value="Trident" />
        <capability name="layoutEngineVersion" value="${layoutVersion}" />
        <capability name="extra" value="${extra}" />
        <capability name="isColor" value="true" />
        <capability name="letters" value="${letters}" />
        <capability name="majorversion" value="${major}" />
        <capability name="minorversion" value="${minor}" />
        <capability name="screenBitDepth" value="8" />
        <capability name="type" value="IE${major}" />
        <capability name="version" value="${version}" />
      </capabilities>
    </browser>

    <!-- Mozilla/5.0 (Windows NT 6.3; Trident/7.0; rv:11,0) like Gecko -->
    <browser id="IE110" parentID="IE11">
      <identification>
        <capability name="majorversion" match="11" />
      </identification>

      <capabilities>
        <capability name="ecmascriptversion" value="3.0" />
        <capability name="jscriptversion" value="5.6" />
        <capability name="javascript" value="true" />
        <capability name="javascriptversion" value="1.5" />
        <capability name="msdomversion" value="${majorversion}.${minorversion}" />
        <capability name="w3cdomversion" value="1.0" />
        <capability name="ExchangeOmaSupported" value="true" />
        <capability name="activexcontrols" value="true" />
        <capability name="backgroundsounds" value="true" />
        <capability name="cookies" value="true" />
        <capability name="frames" value="true" />
        <capability name="javaapplets" value="true" />
        <capability name="supportsCallback" value="true" />
        <capability name="supportsFileUpload" value="true" />
        <capability name="supportsMultilineTextBoxDisplay" value="true" />
        <capability name="supportsMaintainScrollPositionOnPostback" value="true" />
        <capability name="supportsVCard" value="true" />
        <capability name="supportsXmlHttp" value="true" />
        <capability name="tables" value="true" />
        <capability name="supportsAccessKeyAttribute" value="true" />
        <capability name="tagwriter" value="System.Web.UI.HtmlTextWriter" />
        <capability name="vbscript" value="true" />
      </capabilities>
    </browser>