Show Visualizers Error “could not load this custom viewer”

Question

When I try to inspect DataSet by standard DataSet visualizer I see this error \"could not load this custom viewer\". I wrote simple dataset visualizer, but

Answer 1

Try the following.

-Go to Tools->options->Debugging->Plz Uncheck "Use Managed Compatibility Mode"

Answer 2

I had the same issue in VS2017, I tried a lot but nothing was worked and finally, I reset all the VS settings which I made and the error was gone.

https://blogs.msdn.microsoft.com/zainnab/2010/07/16/reset-all-your-development-settings/

Answer 3

visual studio -> Tools-> options-> Debugging-> "Use Managed Compatibility Mode" - uncheck this and maybe it works fine then.

Answer 4

in visual studio 2019 community after an update between 16.4.x - 16.7.5 mine was broken all I had to do was uncheck "Warn when using custom debugger visualizers against potentially unsafe processes (Managed only)" and it allowed me to see a visual of the datatable. Under the tools>options>Debugging>general menu.

Answer 5

For me, I had written my own visualizer for a type that I had created. Apparently, this was interfering with VS 2017's ability to display the built-in visualizer for datasets. Once I removed my own visualizer and the Microsoft Debugger Visualizer reference, I could use the built-in ones.
I have written other visualizers in earlier versions of VS that didn't cause any problems.

Answer 6

I found workaround! I changed source code of DevExpress module and recompile it. After that I undo parameter to NetFx40_LegacySecurityPolicy enabled="false", and enjoy. :)

File is "%DeveloperExpress.NET%\Sources\DevExpress.Data\Utils\Security.cs"

using System;
using System.Security;
using System.Security.Permissions;
namespace DevExpress.Data.Helpers {
    public static class SecurityHelper {
        public static bool IsPartialTrust {
            get {
                return !IsPermissionGranted(new ReflectionPermission(ReflectionPermissionFlag.MemberAccess));
            }
        }
        public static bool IsPermissionGranted(IPermission permission) {
            bool result = true;
/* (changed by Lion)
            try {
                PermissionSet ps = SecurityManager.ResolvePolicy((System.Security.Policy.Evidence)null);
                ps = ps.Copy();
                ps.AddPermission(permission);
                ps.Demand();
            }
            catch (SecurityException) {
                result = false;
            }
*/
            return result;
        }
    }
}