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Knowledge Base / Designer / Unhandled Exception Sequel Viewpoint Loader Breaks Designer
Unhandled Exception Sequel Viewpoint Loader Breaks Designer
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Created/Edited - 5/8/2026 by Brady Weatherly | Alteryx

Summary
The Sequel Viewpoint software is breaking Designer from loading.
Environment
  • Alteryx Designer
    • 2020.2+
    • Sequel ViewPoint

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Cause

The Sequel Viewpoint software is installing an older version of Newtonsoft.Json into the .NET global assembly cache. This is forcing Designer to load the 12.0.0 version of the Newtonsoft.Json.dll from the  .NET GAC.  Because Designer uses version 12.0.1 it is causing random errors when loading. 

https://docs.microsoft.com/en-us/troubleshoot/dotnet/framework/install-assembly-global-assembly-cache


Message: 'Newtonsoft.Json.Linq.JObject' does not contain a definition for 'UseClassicMode

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Resolution

Download the 12.0.1 version from the link below and use the .net45 version and copy it over the 12.0.0 in the C:\Windows\assembly\GAC_MSIL\Newtonsoft.Json.

NuPKG files are just zip files, so anything that can process a zip file should be able to process a nupkg file, i.e, 7zip.


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https://www.nuget.org/packages/Newtonsoft.Json/12.0.1
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