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Type not found exception after updating to the newest .net core preview8


I have updated my Visual Studio to the newest version and have installed the newest .net core 3.0 preview 8. In my MainLayout i have several syncfusion controls, menu, treeview and dropdowns. When i start the project i get an exception:

 "Could not load type 'Microsoft.AspNetCore.Components.UIFocusEventArgs' from assembly 'Microsoft.AspNetCore.Components, Version="

When i remove all the dropdownlists from MainLayout the app starts without an exception or error, but also the treeview is not rendered but the menu shows up.
So the error seems to be in the dropdownlists, is there any solutio for that right now or must i downgrade to preview7 ?

Best regards
Christoph Weller

12 Replies

SL Steven Littleford August 14, 2019 11:32 AM UTC

I am getting a similar issue - although even preview 7 had the issue., 
It started when i upgraded to VFS2019 Preview 2.

No everything is a brick. I'm dead in the water

DW Dominic Williams August 15, 2019 02:47 AM UTC

I am facing the same issue.  None of the components that I am using work.  There are a few breaking changes in preview8, some impacting jsinterop, like ElementRef being renamed to ElementRefrence. 

GG Gopi Govindasamy Syncfusion Team August 15, 2019 07:41 AM UTC

Hi All, 

Greetings from Syncfusion support. 

We are able to understand that you are facing issue with our Syncfusion components, We suspect that you are facing issue after updating the .Net Core 3.0 to Preview 8 build. We have confirmed that you have upgraded to latest version of .Net Core by the sample provided. Currently we (Syncfusion components) do not have support for .NET CORE 3.0 Preview 8. But the reported issue occur due to changes in .Net Core 3.0 Preview 8 build. Refer the below link for your reference. 

We are in process of migrating our components to Preview 8. It will be implemented in our upcoming Nuget release which is expected to be rolled on or before 21st August 2019. Till then we appreciate your patience. 

Gopi G. 

PB Peter Benedix August 15, 2019 07:48 AM UTC

Thanks for this information but this is quite hard. We've purchaced a license two weeks ago for Syncfusion Blazor and now it's useless until the middle of next week. We have suspected, that Syncfusion is a little bit faster in handeling such situations. That can kill a project pipeline.

DW Dominic Williams August 15, 2019 09:25 PM UTC

Looking at the full stack trace, my initial suspicions were correct... it's due to ElementRef being renamed to ElementReference

Unable to load one or more of the requested types.
Could not load type 'Microsoft.AspNetCore.Components.UIMouseEventArgs' from assembly 'Microsoft.AspNetCore.Components, Version=, Culture=neutral, PublicKeyToken=adb9793829ddae60'.
Could not load type 'Microsoft.AspNetCore.Components.ElementRef' from assembly 'Microsoft.AspNetCore.Components, Version=, Culture=neutral, PublicKeyToken=adb9793829ddae60'.

I suppose there are some other breaking changes, but that seems to be the main one.

SN Sridhar N Syncfusion Team August 16, 2019 07:58 AM UTC

Hi All,

We have created a private NuGet for preview 8 support and please find the attachment
Thanks for your patience and we will deliver the patch release as promised after our testing. 
Note: Clear NuGet cache and refer the local NuGet and use ejs.interop.min.js as a local reference instead of CDN reference.  
Sridhar N

PB Peter Benedix August 16, 2019 11:22 AM UTC

Thanks, but it's not working: 

      Unhandled exception rendering component: Could not load type 'Microsoft.AspNetCore.Components.UIFocusEventArgs' from assembly 'Microsoft.AspNetCore.Components, Version=, Culture=neutral, PublicKeyToken=adb9793829ddae60'.
System.TypeLoadException: Could not load type 'Microsoft.AspNetCore.Components.UIFocusEventArgs' from assembly 'Microsoft.AspNetCore.Components, Version=, Culture=neutral, PublicKeyToken=adb9793829ddae60'.
   at _2027_1_bmw_futureforum_backend.Pages.Ticker.BuildRenderTree(RenderTreeBuilder builder)
   at Microsoft.AspNetCore.Components.ComponentBase.<.ctor>b__5_0(RenderTreeBuilder builder)
   at Microsoft.AspNetCore.Components.Rendering.ComponentState.RenderIntoBatch(RenderBatchBuilder batchBuilder, RenderFragment renderFragment)

Maybe it's the wrong file? The Name is equal to the current version for Preview7.

SP Scott Peal August 16, 2019 05:04 PM UTC

For my project I had to remove one of the usings in _import. And change all the OnInt / OnIntAsync calls as well as the ElementRef. Once those were all changed basically using search and replace my project was up and running in about 20 minutes. Except for the Syncfusion controls of course. My project has a very large code base moving towards production in 60 days or so.

MA Mr Andrey Voronov August 19, 2019 08:50 AM UTC

This local NuGet package fixed "Could not load type..." exception but:

a) Grid has TValue set but it does not display template columns 

<EjsGrid ...>

b) Getting System.InvalidOperationException: Object of type 'Syncfusion.EJ2.Blazor.Grids.EjsGrid`1[[Elht.DbPatientData, ElhtDbPatient, Version=, Culture=neutral, PublicKeyToken=null]]' does not have a property matching the name '@ref:suppressField'.

when using backing field

<EjsGrid  @ref:suppressField="@patientselectgrid"...

UH Uwe Hein August 19, 2019 09:37 AM UTC



<EjsGrid  @ref="patientselectgrid" @ref:suppressField .....

instead of

<EjsGrid  @ref:suppressField="@patientselectgrid"...

At least this is working with scheduler ...



MA Mr Andrey Voronov August 19, 2019 09:59 AM UTC

<EjsGrid  @ref="patientselectgrid"...> does not work on EjsGrid:

Using '@ref' on generic-type component requires manually defining a field.. Use '@ref:suppressField ...

Also I am now getting 

System.ArgumentException: Property set method not found.
   at System.Reflection.RuntimePropertyInfo.SetValue(Object obj, Object value, BindingFlags invokeAttr, Binder binder, Object[] index, CultureInfo culture)
   at System.Reflection.RuntimePropertyInfo.SetValue(Object obj, Object value, Object[] index)
   at Syncfusion.EJ2.Blazor.BaseComponent.GetObject(Dictionary`2 Data, Type ModelType)
   at Syncfusion.EJ2.Blazor.BaseComponent.GetObject(Dictionary`2 Data, Type ModelType)
   at Syncfusion.EJ2.Blazor.Grids.GridColumn.BuildRenderTree(RenderTreeBuilder builder)
   at Microsoft.AspNetCore.Components.ComponentBase.<.ctor>b__5_0(RenderTreeBuilder builder)
   at Microsoft.AspNetCore.Components.Rendering.ComponentState.RenderIntoBatch(RenderBatchBuilder batchBuilder, RenderFragment renderFragment)
   at Microsoft.AspNetCore.Components.Rendering.Renderer.RenderInExistingBatch(RenderQueueEntry renderQueueEntry)
   at Microsoft.AspNetCore.Components.Rendering.Renderer.ProcessRenderQueue()

when using templated column



VN Vignesh Natarajan Syncfusion Team August 19, 2019 01:10 PM UTC

Hi Mr Andrey, 

Query 1 : <EjsGrid  @ref="patientselectgrid"...> does not work on EjsGrid: 
We would like you to use the below code as suggested by Uwe Hein to overcome the problem you are facing.  

<EjsGrid  @ref="patientselectgrid" @ref:suppressField .....> </EjsGrid  

Query2: “Grid has TValue set but it does not display template columns” && “System.ArgumentException: Property set method not found. 

Currently we don’t have support for read only properties in Column template. So we have confirmed this as an issue and logged a defect report for the same. At Syncfusion, we are committed to fixing all validated defects (subject to technological feasibility and Product Development Life Cycle ) and including the defect fix in our subsequent Nuget release which is expected to be roll out on or before August 21st  2019.  

You can now track the current status of your request, review the proposed resolution timeline, and contact us for any further inquiries through this link.  
Please get back to us if you need further assistance. 

Vignesh Natarajan.

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