[解決]ASP.NET 的工作階段狀態已禁用。報表檢視器控制項要求在本地模式下啟用工作階段狀態。

問題現象：

添加Report WebPart後頁面不能顯示，查看日誌有如下訊息：
中文：ASP.NET 的工作階段狀態已禁用。報表檢視器控制項要求在本地模式下啟用工作階段狀態。
英文：Session state has been disabled for ASP.NET. The Report Viewer control requires that session state be enabled in local mode

解決辦法：

參看如下文章：http://ranaictiu-technicalblog.blogspot.com/2010/04/sharepoint-2010-configure-rdlc-report.html

Tuesday, April 20, 2010
SharePoint 2010: Configure RDLC report with ReportViewer
I have worked with SharePoint 2010 beta 2 and found the RDL(C) report is not configured automatically.  To run a sample report I did the following things. To make sure the configuration works for reporting just put a reportviewer control inside a webpart/page and try to access the page. First of all make sure you have intalled “Microsoft Report Viewer 2010 Redistributable Package”. You can download Microsoft Report Viewer 2010 Redistributable Package from http://www.microsoft.com/downloads/details.aspx?FamilyID=a941c6b2-64dd-4d03-9ca7-4017a0d164fd&displaylang=en.

Here are the steps to configure the SharePoint for report:

1. First find the following line in AppSettings and comment it out as shown below:

  <!--<add key="ReportViewerMessages" value="Microsoft.SharePoint.Portal.Analytics.UI.ReportViewerMessages, Microsoft.SharePoint.Portal, Version=14.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c" />-->

2. By default session is disabled in SharePoint. Enable it by ensuring an entry like below inside <system.web>.

<sessionState mode="InProc" timeout="60" />  
3. Enable session at page level by setting the enableSessionState to true of <page…..> tag inside system.web.
<pages enableSessionState="true" enableViewState="true" enableViewStateMac="true" validateRequest="false" ……………………=""
4. SharePoint disable the default session module inside the <system.webserver>\modules tag. To enable the module comment out the following line inside <system.webserver>\moudles as shown below:
<!--<remove name="Session" />-->  
Now if you try to put a reportviewer control you will find a message like below:
 
If you find the above error then follow the steps 5, 6 and 7:
5. Add the following tag inside system.web\httphandlers section
<add verb="*" path="Reserved.ReportViewerWebControl.axd" type = "Microsoft.Reporting.WebForms.HttpHandler, Microsoft.ReportViewer.WebForms, Version=10.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" />  
6. Add the following line in the system.webserver\handlers 
<add name="ReportViewerWebControlHandler" preCondition="integratedMode" verb="*" path="Reserved.ReportViewerWebControl.axd" type="Microsoft.Reporting.WebForms.HttpHandler, Microsoft.ReportViewer.WebForms, Version=10.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" />  
7. Comment out the following line in the system.WebServer\httphandlers (If Exists)
<!--<add name="ReportViewerWebControl" verb="*" path="Reserved.ReportViewerWebControl.axd" type="Microsoft.Reporting.WebForms.HttpHandler, Microsoft.ReportViewer.WebForms, Version=8.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" />—>   
And finally it worked………..