We have checked with our side, sample is working fine. From the provided stack trace information, we suspect that some assembly versions (Syncfusion.Diagram.WPF and Syncfusion.Core) are not referred correctly.
Kindly check whether the correct version is referred.
To check, right click on the assembly (Syncfusion.Diagram.WPf, Syncfusion.Core) under References. Click properties and see the version number. And change Specific version to false.
Now delete bin and obj files, rebuild the application.
We also show this in provided screen shot. Kindly refer from attachment.
We are unable to reproduce the reported issue in our side. However, please follow the below suggestions.
1. We suspect that there may be mismatched version of dlls referred in your application (among 11.2045.0.25 & 220.127.116.11). So, we are suggesting you to please remove the 11.2 assemblies from GAC by run the Assembly Manager.
For more information about the Assembly Manager, please refer our documentation using the below link.
2. Please set ‘Specific Version’ as true for all 3 dlls (Syncfusion.Core, Diagram, Shared dlls) and then compile the application.
Still if you face the issue, please provide the diagram dependent assemblies (Syncfusion.Core, Diagram, Shared dlls) which you are currently using. We will check internally and will provide the appropriate information once you provided the assemblies.
Please let us know if you have any concerns on this.