Resolving the “Could not load type 'System.ServiceModel.Activation.HttpModule'“error
This issue may arise if you have installed Syncfusion Essential Studio with all the product components including Silverlight in the IIS-configured machine. This is a known issue, and it will be fixed starting from version 11.x.x.xx of Syncfusion Essential Studio.
As a workaround, you can resolve it by running Aspnet_regiis.exe with the below arguments to re-register the correct version of ASP.NET in the IIS web server.
1) Open the command prompt with administrative privileges and navigate to the the Aspnet_regiis.exe file, which can be found in one of the following locations:
2) Run Aspnet_regiis.exe with the following arguments: aspnet_regiis.exe /iru
3) Refresh the IIS web server or run the iisreset command in admin mode and restart the Syncfusion dashboard.
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