The type or namespace name 'CrystalReportViewer' does not exist in the namespace 'CrystalDecisions.Web' (are you missing an assembly reference?)

问题

I'm getting the following error on using crystal report in my asp.net 3.5 a3-tier application

The type or namespace name 'CrystalReportViewer' does not exist in the namespace 'CrystalDecisions.Web' (are you missing an assembly reference?)

the namespaces I have included are:

using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Xml.Linq;
using MorvelNew.Report;
using System.Data.Sql;
using System.Data.SqlClient;
using System.Data.SqlTypes;
using CrystalDecisions.CrystalReports.Engine;
using CrystalDecisions.Web;

回答1:

Right-click on "References" and select "Add Reference..."
Go to "Extensions"
Find "CrystalDecisions.Web"

and add namespace.

回答2:

missed few assemblies in web.config

    <add assembly="CrystalDecisions.ReportAppServer.ClientDoc, Version=10.5.3700.0, Culture=neutral, PublicKeyToken=692fbea5521e1304"/>
    <add assembly="CrystalDecisions.Enterprise.Framework, Version=10.5.3700.0, Culture=neutral, PublicKeyToken=692fbea5521e1304"/>

<add assembly="CrystalDecisions.Web, Version=10.5.3700.0, Culture=neutral, PublicKeyToken=692FBEA5521E1304"/>
<add assembly="CrystalDecisions.Shared, Version=10.5.3700.0, Culture=neutral, PublicKeyToken=692FBEA5521E1304"/>
<add assembly="CrystalDecisions.ReportSource, Version=10.5.3700.0, Culture=neutral, PublicKeyToken=692FBEA5521E1304"/>
<add assembly="CrystalDecisions.CrystalReports.Engine, Version=10.5.3700.0, Culture=neutral, PublicKeyToken=692FBEA5521E1304"/>
    <add assembly="CrystalDecisions.ReportAppServer.ClientDoc, Version=10.5.3700.0, Culture=neutral, PublicKeyToken=692fbea5521e1304"/>
    <add assembly="CrystalDecisions.Enterprise.Framework, Version=10.5.3700.0, Culture=neutral, PublicKeyToken=692fbea5521e1304"/>
    <add assembly="CrystalDecisions.Enterprise.InfoStore, Version=10.5.3700.0, Culture=neutral, PublicKeyToken=692fbea5521e1304"/></assemblies>

来源：https://stackoverflow.com/questions/11700176/the-type-or-namespace-name-crystalreportviewer-does-not-exist-in-the-namespace