It likes like after your blazor WASM loaded, the bootstrap js file called load (program.cs) and the init code threw an error creating an object with a constructor that takes a KeyValuePair2 parameter, which is null.
KeyValuePair Issue in Blazor Web App .Net 8 after publish
Prathamesh Shende
511
Reputation points
I am getting issue after publish to the hosting
KeyValuePair2
How do i find where is this issue in project?
Error: AggregateException_ctor_DefaultMessage (ConstructorContainsNullParameterNames, System.Collections.Generic.KeyValuePair2[System.String,System.String])
blazor.web.js:1:156332
callEntryPoint https://clinix.innovustech.in/_framework/blazor.web.js:1
ti https://clinix.innovustech.in/_framework/blazor.web.js:1
ei https://clinix.innovustech.in/_framework/blazor.web.js:1
startWebAssemblyIfNotStarted https://clinix.innovustech.in/_framework/blazor.web.js:1
resolveRendererIdForDescriptor https://clinix.innovustech.in/_framework/blazor.web.js:1
determinePendingOperation https://clinix.innovustech.in/_framework/blazor.web.js:1
refreshRootComponents https://clinix.innovustech.in/_framework/blazor.web.js:1
rootComponentsMayRequireRefresh https://clinix.innovustech.in/_framework/blazor.web.js:1
(Async: setTimeout handler)
rootComponentsMayRequireRefresh https://clinix.innovustech.in/_framework/blazor.web.js:1
startLoadingWebAssemblyIfNotStarted https://clinix.innovustech.in/_framework/blazor.web.js:1
registerComponent https://clinix.innovustech.in/_framework/blazor.web.js:1
Ki https://clinix.innovustech.in/_framework/blazor.web.js:1
Ki https://clinix.innovustech.in/_framework/blazor.web.js:1
(Async: EventListener.handleEvent)
Ji https://clinix.innovustech.in/_framework/blazor.web.js:1
<anonymous> https://clinix.innovustech.in/_framework/blazor.web.js:1
<anonymous> https://clinix.innovustech.in/_framework/blazor.web.js:1
Developer technologies | .NET | Blazor
Accepted answer
-
![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(211.20000000000002, 61%, 30%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EBS%3C/text%3E%3C/svg%3E)
Bruce (SqlWork.com) 79,101 Reputation points Volunteer Moderator2025-07-29T19:02:35.65+00:00 -
Prathamesh Shende 511 Reputation points
2025-07-30T03:34:21.47+00:00 how to solve this issue then? I didn't use KeyValuePair in my code.
-
Bruce (SqlWork.com) 79,101 Reputation points Volunteer Moderator
2025-07-30T17:19:50.02+00:00 your app is throwing an exception at startup, but does perform any logging. The generic KeyValuePair<> is pretty common.
in your program try:
var app = builder.Build(); var js = app.Services.GetRequiredService<IJSRuntime>(); await js.InvokeVoidAsync("console.log", "Blazor WebAssembly app started successfully!"); await app.RunAsync();if the message appears in the console, then your code throwing exception in page load, if the message does not appear then before or during app.Build()
-
Prathamesh Shende 511 Reputation points
2025-07-30T17:23:54.6733333+00:00 Okay I will try this, thanks
Sign in to comment -