.NET Questions and Solutions

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Entries for November, 2010

FIX: Access Violation When You Migrate MTS Application to COM+

Symptoms
When you migrate a Microsoft Transaction Server (MTS) application to COM+, and you do not call the SetComplete or SetAbort method, an Access Violation may occur, and the application may fail (crash). This problem occurs in COM+ (Windows 2000 Service Pack 1) and not in MTS.
Resolution
This problem occurs when non-root transactional objects release the object reference to their parent object and do not call SetComplete or SetAbort explicitly at the end of the method.
This problem is caused by a difference in the activation and deactivation mechanisms between COM+ and MTS. In COM+, if the child object does not set the done bit to true (if it does not call the IObjectControl::SetComplete or the IObjectControl::SetAbort method, does not call the IContextState:setCompletion method, or does not use Auto-Completion), the COM+ interception layer deactivates the parent object before the child object. In fact, you do not need to set the done bit, even if it is preferred in most situations.

FIX: A Windows Forms application that uses ActiveX controls may crash, and a null reference exception occurs after you install the .NET Framework 2.0 Service Pack 1

Symptoms
After you install the Microsoft .NET Framework 2.0 Service Pack 1, a Windows Forms application that uses Microsoft ActiveX controls may crash. When this problem occurs, a null reference exception occurs. Additionally, the following call stack is generated in the Windows Forms application:

System.NullReferenceException: Object reference not set to an instance of an object.at System.Windows.Forms.AxHost.OleInterfaces.AttemptStopEvents(Object trash)at System.Threading._ThreadPoolWaitCallback.WaitCallback_Context(Object state)at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)at System.Threading._ThreadPoolWaitCallback.PerformWaitCallbackInternal(_ThreadPoolWaitCallback tpWaitCallBack)at System.Threading._ThreadPoolWaitCallback.PerformWaitCallback(Object state)
Resolution
Hotfix informationA supported hotfix is now available from Microsoft. However, it is intended to correct only the problem that is described in this article. Apply it only to systems that are experiencing this specific problem. This hotfix may receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next .NET Framework 2.0 service pack that contains this hotfix.
To resolve this problem immediately, contact Microsoft Customer Support Services to obtain the hotfix. For a complete list of Microsoft Customer Support Services telephone numbers and information about support costs, visit the following Microsoft Web site:
http://support.microsoft.com/contactus/?ws=support(http://support.microsoft.com/contactus/?ws=support)Note In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual support costs will apply to additional support questions and issues that do not qualify for the specific update in question.Prerequisites To apply this hotfix, you must have the .NET Framework 2.0 Service Pack 1 installed. Restart requirementYou do not have to restart the computer after you apply this hotfix.Hotfix replacement informationThis hotfix does not replace any other hotfixes.File information The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time item in Control Panel.
Collapse this tableExpand this table
File nameFile versionFile sizeDateTimePlatformSystem.windows.forms.dll2.0.50727.18195,173,24814-3-200803:40×86

FIX: A System.NullReferenceException exception occurs when you deploy a composite database project in Microsoft Visual Studio Team System 2008 Database Edition GDR

Symptoms
Consider the following scenario in Microsoft Visual Studio Team System 2008 Database Edition GDR: You have a database project that includes tables.You have another database project that includes constraints for the tables in the same solution and you add a reference to the database project that includes tables.You connect both projects to the same target database on a server.Then, you deploy the projects to the database.In this scenario, you receive a System.NullReferenceException exception and then the Visual Studio IDE crashes. If you debug this exception, you receive the following error message:

System.NullReferenceException: Object reference not set to an instance of an object.
Resolution
To resolve this problem, upgrade to Microsoft Visual Studio Team System 2008 Database Edition GDR R2. For more information, click the following article number to view the article in the Microsoft Knowledge Base:
970479?(http://support.microsoft.com/kb/970479/) List of fixed issues in the Microsoft Visual Studio Team System 2008 Database Edition GDR R2
Note Microsoft Visual Studio Team System 2008 Database Edition GDR R2 replaces Microsoft Visual Studio Team System 2008 Database Edition GDR.