Could not load type 'System.ValueTuple`2' from assembly 'mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'

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Posted on by Patrick74

Hi,
I use Visual Studio 2017, .NET Framework 4.7.1 and Dynamics CRM online 9.0.2.

In code I use the ValueTuple introduced in .NET Framework 4.7.
For example:

var retValue = (retCode: statusCode, retMsg: result);

The plugin can be properly registered using the Plugin Registration Tool.

When the plugin is executed, the following error message is displayed:
Could not load type 'System.ValueTuple`2' from assembly 'mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'.
According to the documentation the CRM supports SDK version 4.6.2 or higher.

Anyone have an idea?

Many thanks in advance
Patrick

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Patrick74 5 on at

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RE: Could not load type 'System.ValueTuple`2' from assembly 'mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'

Hi Sergio,

Thanks for your answer. Then I will return to 4.6.2.

Best Regards

Patrick
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SergioMarques on at

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RE: Could not load type 'System.ValueTuple`2' from assembly 'mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'

Hi Patrick,

Can you try to build the plugin with .Net Framework version 4.6.2 ?

Although the recommend version for custom client applications (console applications) is 4.7.2

https://docs.microsoft.com/en-us/dynamics365/customerengagement/on-premises/developer/visual-studio-dot-net-framework

The .NET SDK assemblies for Dynamics 365 for Customer Engagement are built on .NET Framework version 4.6.2.

You can use Visual Studio to build your managed code applications using .NET Framework version 4.6.2 or later.

The recommended version for plugins and custom workflow activities is 4.6.2.

https://docs.microsoft.com/en-us/powerapps/developer/common-data-service/write-plug-in

Use .NET Framework 4.6.2

Plug-ins and custom workflow assemblies should use .NET Framework 4.6.2. While assemblies built using later versions should generally work, if they use any features introduced after 4.6.2 an error will occur.

Thank you.

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Could not load type 'System.ValueTuple`2' from assembly 'mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'

Use .NET Framework 4.6.2

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Could not load type 'System.ValueTuple`2' from assembly 'mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'

Use .NET Framework 4.6.2

Helpful resources

Quick Links

🌸 Community Spring Festival 2025 Challenge Winners! 🌸

Adis Hodzic – Community Spotlight

Kudos to the April Top 10 Community Stars!

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