FIX: Error message when a "System.Data" thread tries to open a pooled connection in the .NET Framework 2.0: "Timeout expired. The timeout period elapsed prior to obtaining a connection from the pool"


Consider the following scenario. In the Microsoft .NET Framework 2.0, a System.Data thread tries to open a pooled connection. At the same time, another thread tries to clear that pool by using the ClearPool method or the ClearAllPools method. In this scenario, you receive the following error message:
Timeout expired. The timeout period elapsed prior to obtaining a connection from the pool. This may have occurred because all pooled connections were in use and max pool size was reached.
This problem occurs in the following versions of the .NET Framework 2.0:
  • The release version of the .NET Framework 2.0
  • The .NET Framework 2.0 Service Pack 1


This problem occurs because of a race condition in the internal call of the GetConnection method. After both the connection pool group and the connection pool are obtained, the GetConnection method is called on the pool. If the ClearPool method is called between the GetConnectionPool method and the GetConnection method, the pool state is changed to ShuttingDown, and the GetConnection method returns the null value. These things occur because of the race condition. Then, because the null value is interpreted as a time-out, you receive the error message that is mentioned in the "Symptoms" section.


Hotfix information

To resolve this problem, install the hotfix that is mentioned in the following article in the Microsoft Knowledge Base:
948815 Availability of the .NET Framework 2.0 post-Service Pack 1 hotfix rollup package for System.Data.dll and System.Data.OracleClient.dll


You must have the .NET Framework 2.0 Service Pack 1 installed to apply this hotfix.

Restart requirement

You do not have to restart the computer after you apply this hotfix.

Hotfix replacement information

This 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.
The .NET Framework 2.0, x86 versions
File nameFile versionFile sizeDateTimePlatform,998,27204-Feb-200820:49x86,35204-Feb-200820:49x86
The .NET Framework 2.0, x64 versions
File nameFile versionFile sizeDateTimePlatform,998,27204-Feb-200820:49x86,35204-Feb-200820:49x86,113,47214-Jan-200815:36x64,71214-Jan-200815:36x64
The .NET Framework 2.0, Itanium-based versions
File nameFile versionFile sizeDateTimePlatform,998,27204-Feb-200820:49x86,35204-Feb-200820:49x86,208,19204-Feb-200817:25IA-64,80804-Feb-200817:25IA-64


Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

More Information

For more information about software update terminology, click the following article number to view the article in the Microsoft Knowledge Base:

824684 Description of the standard terminology that is used to describe Microsoft software updates

Call stack information

System.Data.ProviderBase.DbConnectionFactory.GetConnection(DbConnection owningConnection)
System.Data.ProviderBase.DbConnectionClosed.OpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory)

ID do Artigo: 948868 - Última Revisão: 08/10/2011 - Revisão: 1