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<startup> Element

Specifies common language runtime startup information.

<configuration> Element
  <startup> Element

<startup useLegacyV2RuntimeActivationPolicy="true|false" > 

Attributes and Elements

The following sections describe attributes, child elements, and parent elements.





Optional attribute.

Specifies whether to enable the .NET Framework version 2.0 runtime activation policy or to use the .NET Framework version 4 activation policy.

useLegacyV2RuntimeActivationPolicy Attribute




Enable .NET Framework version 2.0 runtime activation policy for the chosen runtime, which is to bind legacy runtime activation techniques (such as the CorBindToRuntimeEx function) to the runtime chosen from the configuration file instead of capping them at CLR version 2.0. Thus, if CLR version 4 or later is chosen from the configuration file, mixed-mode assemblies created with earlier versions of the .NET Framework are loaded with the chosen CLR version. Setting this value prevents CLR version 1.1 or CLR version 2.0 from loading into the same process, effectively disabling the in-process side-by-side feature.


Use the default activation policy for the .NET Framework 4 and later, which is to allow legacy runtime activation techniques to load CLR version 1.1 or 2.0 into the process. Setting this value prevents mixed-mode assemblies from loading into the .NET Framework 4 or later unless they were built with the .NET Framework 4 or later. This value is the default.

Child Elements




Specifies that the application supports only version 1.0 of the common language runtime. Applications built with runtime version 1.1 or later should use the <supportedRuntime> element.


Specifies which versions of the common language runtime the application supports.

Parent Elements




The root element in every configuration file used by the common language runtime and .NET Framework applications.


The <supportedRuntime> element should be used by all applications built using version 1.1 or later of the runtime. Applications built to support only version 1.0 of the runtime must use the <requiredRuntime> element.

The startup code for an application hosted in Microsoft Internet Explorer ignores the <startup> element and its child elements.

The useLegacyV2RuntimeActivationPolicy Attribute

This attribute is useful if your application uses legacy activation paths, such as the CorBindToRuntimeEx function, and you want those paths to activate version 4 of the CLR instead of an earlier version, or if your application is built with the .NET Framework 4 but has a dependency on a mixed-mode assembly built with an earlier version of the .NET Framework. In those scenarios, set the attribute to true.


Setting the attribute to true prevents CLR version 1.1 or CLR version 2.0 from loading into the same process, effectively disabling the in-process side-by-side feature (see Side-by-Side Execution for COM Interop).


The following example shows how to specify the runtime version in a configuration file.

<!-- When used with version 1.0 of the .NET Framework runtime -->
      <requiredRuntime version="v1.0.3705" safemode="true"/>
<!-- When used with version 1.1 (or later) of the runtime -->
      <supportedRuntime version="v1.1.4322"/>
      <supportedRuntime version="v1.0.3705"/>

See Also


Startup Settings Schema


Specifying Which Runtime Version to Use

In-Process Side-by-Side Execution

Other Resources

Configuration File Schema for the .NET Framework

Side-by-Side Execution for COM Interop