It is very likely that the Essential Diagram application that you copied over to the remote server does not have the web.config file from the Essential Studio installation. Essential Diagram uses the web configuration file to specify the custom httphandler that it uses for rendering the diagram image. The sample when run from the default installation directory will pick up the configuration information from the '\Syncfusion\Essential Studio\3.2...\web.config' file that is shared by all the Syncfusion ASP.NET samples. Open the sample project on the remote server in VS.NET and use the Add New Item dialog to add a web.config file to the sample, and update it with a httphandler entry like the one present in the attached configuration file. Please be sure to specify the correct version information for the Syncfusion.Diagram.Web assembly. This should make the sample work as expected.
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