Request is not available in this context

Request is not available in this context

<system.web>
<customErrors mode="Off" />

<authentication mode="Forms">
<forms loginUrl="~/home" timeout="30" slidingExpiration="true" />
</authentication>
<pages asyncTimeout="60" />
<compilation targetFramework="4.5" />
<httpRuntime targetFramework="4.5" maxRequestLength="2097151" executionTimeout="6000" />
<sessionState mode="StateServer" timeout="120" cookieless="false" />
<globalization requestEncoding="utf-8" responseEncoding="utf-8" fileEncoding="utf-8" culture="zh-cn" />
</system.web>