How to troubleshoot server and client exceptions in Blazor

29 Nov 20249 minutes to read

Runtime exceptions

InvalidOperationException: Cannot provide a value for property ‘SyncfusionService’ on type ‘Syncfusion.Blazor.Namespace.Component’

You may see the below runtime exception while running the application for the first time.

ERROR

InvalidOperationException: Cannot provide a value for property ‘SyncfusionService’ on type ‘Syncfusion.Blazor.Namespace.Component’. There is no registered service of type ‘Syncfusion.Blazor.SyncfusionBlazorService’.

Cause:

This exception thrown because you missed registering the SyncfusionBlazorService in Program.cs.

Solution:

You can register the SyncfusionBlazorService in Program.cs file to resolve the exception.
```
  using Syncfusion.Blazor;
  ....
  builder.Services.AddSyncfusionBlazor();
```
System.NullReferenceException: Object reference not set to an instance of an object

You may see the below exception while running the application in your production/server machine.

ERROR

System.NullReferenceException: Object reference not set to an instance of an object.
at Syncfusion.Blazor.SyncfusionBlazorService.GetContext()

at Syncfusion.Blazor.BaseComponent.OnInitializedAsync()

at Syncfusion.Blazor.Charts.SfChart.OnInitializedAsync()

at Microsoft.AspNetCore.Components.ComponentBase.RunInitAndSetParametersAsync()

Cause:

The production/hosting server machine may have an outdated configuration like .NET Core SDK and .NET Core runtime hosting bundle.

Solution:

Update your dotnet SDK/hosting bundle with the latest version in your production/hosting server machine.

Install the latest dotnet SDK/hosting bundle from here in your hosting machine to resolve this.
The type name ‘Shared’ does not exist in the type ‘SyncfusionBlazor’

You may see the below exception while running the Syncfusion^® blazor
application.

ERROR

The type name ‘Shared’ does not exist in the type ‘SyncfusionBlazor’ SyncfusionBlazor \SyncfusionBlazor\SyncfusionBlazor\obj\Debug\netcoreapp3.1\Razor\Shared\MainLayout.razor.g.cs

Cause:

This issue occurred, if you are creating the application name as SyncfusionBlazor. The name SyncfusionBlazor is already registered in the Syncfusion^® service handling. So your application name and the internally used class name gets conflict.

Solution:

Try to use a different application name, when you create the blazor application with Syncfusion^® Blazor components.
System.IO.FileLoadException: Could not load file or assembly ‘System.Text.Json

You may get the below exception while running the Syncfusion^® blazor application.

ERROR

System.IO.FileLoadException: Could not load file or assembly ‘System.Text.Json, Version=4.0.1.1, Culture=neutral PublicKeyToken=cc7b13ffcd2ddd51’. The located assembly’s manifest definition does not match the assembly reference.

Cause:

You may have .NET Core SDK older than version 3.1.2, but Syncfusion^® Blazor components need the latest version of .NET Core SDK as stated in the pre-requisite documentation.

Solution:

Check installed .NET Core SDK version and update to the latest version. You can also find/download the details of the latest .NET Core SDK version here.

Compile-time errors

error CS0121: The call is ambiguous between the following methods or properties: ‘Syncfusion.Blazor.SyncfusionBlazor.AddSyncfusionBlazor(Microsoft.Extensions.DependencyInjection.IServiceCollection, bool)’ and ‘Syncfusion.Blazor.SyncfusionBlazor.AddSyncfusionBlazor(Microsoft.Extensions.DependencyInjection.IServiceCollection, bool)’

You may see the below compile-time exception while running the application.

ERROR

The call is ambiguous between the following methods or properties ‘Syncfusion.Blazor.SyncfusionBlazor.AddSyncfusionBlazor(Microsoft.Extensions.DependencyInjection.IServiceCollection, bool)’

Cause:
1. You may used SfPdfViewer or SfDocumentEditor components along with other Syncfusion^® Blazor components in your application.
2. You may installed both Syncfusion.Blazor and individual NuGet packages in the same application.
Solution
1. Starts with Volume 4, 2020 (v18.4.0.30) release, The SfPdfViewer and SfDocumentEditor components changed its dependency structure.
2. We suggest you to use the individual NuGet packages to resolve this issue.
The type or namespace name ‘EJ2’ does not exist in the namespace ‘Syncfusion’ (are you missing an assembly reference?)

You may see the below compile-time exception while running the application.

ERROR

The type or namespace name ‘EJ2’ does not exist in the namespace ‘Syncfusion’ (are you missing an assembly reference?)

Cause:

You may use deprecated namespace in the application with Syncfusion^® Blazor NuGet package version greater than or equal to 18.1.0.36.

Solution

The Syncfusion^® Blazor library has changed its namespace, NuGet package name, component name from v18.1.0.36. Refer this documentation to migrate your application with correct namespace. Example: Syncfusion.EJ2.Blazor is now modified as Syncfusion.Blazor.
Found markup element with unexpected name ‘Ejs’. If this is intended to be a component, add a @using directive for its namespace

You may see the below compile-time exception while running the application.

ERROR

Found markup element with unexpected name ‘Ejs’. If this is intended to be a component, add a @using directive for its namespace

Cause:

You may use the deprecated component name in the application with the Syncfusion^® Blazor NuGet package version greater than or equal to 18.1.0.36.

Solution

The Syncfusion^® Blazor library has changed its namespace, NuGet package name and component name from v18.1.0.36. Refer this documentation to migrate your application with correct component name. Example: EjsGrid is now modified as SfGrid.

Browser console errors

net::ERR_ABORTED 404 Error While Using Syncfusion^® Blazor Static CSS

You may see the below exception in the web browser dev tool console.

ERROR

GET ./_content/Syncfusion.Blazor/styles/bootstrap4.css net::ERR_ABORTED 404

Cause:

If you upgraded Syncfusion^® Blazor packages from previous versions to 18.4.0.* version or later, this issue occurred.

Solution

The Syncfusion^® Blazor library provides individual NuGet packages from the 18.4.0.30 version. If you are using individual NuGet Package in your application, you have to modify the below static web assets (styles) reference from Syncfusion.Blazor to Syncfusion.Blazor.Themes in the application to resolve this issue.
```
      <head>
           ....
           ....
           <link href="_content/Syncfusion.Blazor.Themes/bootstrap4.css" rel="stylesheet" />
      </head>
```
NOTE

Do not use both Syncfusion.Blazor and individual NuGet packages in the same application. It will throw ambiguous errors while compiling the project.
An unhandled exception has occurred. See browser dev tools for details

You may see the below exception at the bottom of the page.

ERROR

An unhandled exception has occurred. See browser dev tools for details

Cause:

There may be script errors thrown in the JS Interop or client script source.

Solution:

Open the browser dev tool by pressing the F12 key and navigate to the Console tab.

Check the console error with the following topics to resolve the issue or report us the console error through our support ticket.
Unhandled exception rendering component: Could not find ‘loadScripts’ in ‘window.sfBlazor’.

You may see the below exception in the web browser dev tool console.

ERROR

Could not find ‘loadScripts’ in ‘window.sfBlazor’.

Cause:

This script error may throws because of browser cache or outdated script reference in the application.

Solution:

We recommend you to clear the browser cache to resolve the above script error in v18.2.0.44 or later.

net::ERR_ABORTED 404 Error While Using Syncfusion^® Blazor Static files in modified base path or hosted as sub path app.

You may face the below exception when deploying the blazor application as Sub application.

ERROR

GET ./<SUB-PATH>/<SUB-PATH>_content/Syncfusion.Blazor/<Scripts and CSSs references> net::ERR_ABORTED 404

For this, we need to configure the Base path configuration in the root application’s Program.cs and _Host.cshtml.

Cause:

For sub-path hosting we need to configure the base path related configuration. If we missed to configure it leads to this errors.

Solution:

We need to configure the base path in our application when we are hosting the app as Sub-URL like below.

In _Host.cshtml File	In Program.cs File
`<base href="/myblazorapp/" />`	`app.UsePathBase("/myblazorapp");`

NOTE

The trailing slash is must for ‘_Host.cshtml’ base path configuration.

For further details, refer Host and deploy ASP.NET Core Blazor topic.

How to troubleshoot server and client exceptions in Blazor

Runtime exceptions

Compile-time errors

Browser console errors

See also