Where can I find the new HybridWebView.js

Question

Where can I find the new HybridWebView.js

Arthur P 90

Hello,

I upgraded my .NET MAUI project from 9 to 10 and now my InvokeDotNet-Method from the HybridWebView.js doesnt work and I found online that the file gets updated, but I cant find the new file in the sample project (https://github.com/dotnet/maui-samples/tree/main/10.0/UserInterface/Views/HybridWebViewDemo). Where can I find it or hasn't it changed?

Thanks

Luigi De Giacomo 0 Reputation points

2026-01-21T15:55:55.1733333+00:00
Hi everyone,

I'm migrating a project to .NET 10 that uses HybridWebView to host a Vue.js application.

In .NET 9, everything worked correctly, but in .NET 10, I'm unable to use the standard InvokeDotNet mechanism. Every time the Vue app tries to call a C# method, I get the following error in the console:Microsoft.Maui.Handlers.HybridWebViewHandler: Error: InvokeDotNet endpoint missing or invalid request header.

Context:

Development Environment: I am using an external development server for Vue (Vite) via npm run dev (e.g., http://localhost:5173).

The Problem: In .NET 10, the hybridwebview.js source is not clearly exposed or customizable as before. It seems the new internal implementation of the handler expects specific security headers or a specific origin that is missing when the request comes from a local Dev Server instead of the app's internal storage.

What I've tried: 1. Using the default window.HybridWebView.InvokeDotNet call. 2. Verified that RawMessageReceivedworks (it's the only way I can currently send data to C#). 3. Attempted to manually recreate the InvokeDotNet fetch call, but it fails due to the missing internal endpoint /_framework/InvokeDotNet.

Questions:

Is there a breaking change in .NET 10 regarding how HybridWebView handles Cross-Origin requests for the InvokeDotNet endpoint?

How can we bypass or configure the "Invalid request header" check when using a Dev Server (Vite/Node) during development?

Is there an updated version of the hybridwebview.js bridge for .NET 10 that we should be using?

The goal is to keep using await InvokeDotNet as we did in .NET 9 without having to rewrite a custom communication bridge using RawMessage.

Thanks in advance for any insights.Hi everyone,

I'm migrating a project to .NET 10 that uses HybridWebView to host a Vue.js application.

In .NET 9, everything worked correctly, but in .NET 10, I'm unable to use the standard InvokeDotNet mechanism. Every time the Vue app tries to call a C# method, I get the following error in the console:Microsoft.Maui.Handlers.HybridWebViewHandler: Error: InvokeDotNet endpoint missing or invalid request header.

Context:

Development Environment: I am using an external development server for Vue (Vite) via npm run dev (e.g., http://localhost:5173).

The Problem: In .NET 10, the hybridwebview.js source is not clearly exposed or customizable as before. It seems the new internal implementation of the handler expects specific security headers or a specific origin that is missing when the request comes from a local Dev Server instead of the app's internal storage.

What I've tried: 1. Using the default window.HybridWebView.InvokeDotNet call. 2. Verified that RawMessageReceivedworks (it's the only way I can currently send data to C#). 3. Attempted to manually recreate the InvokeDotNet fetch call, but it fails due to the missing internal endpoint /_framework/InvokeDotNet.

Questions:

Is there a breaking change in .NET 10 regarding how HybridWebView handles Cross-Origin requests for the InvokeDotNet endpoint?

How can we bypass or configure the "Invalid request header" check when using a Dev Server (Vite/Node) during development?

Is there an updated version of the hybridwebview.js bridge for .NET 10 that we should be using?

The goal is to keep using await InvokeDotNet as we did in .NET 9 without having to rewrite a custom communication bridge using RawMessage.

Thanks in advance for any insights.
Jack Dang (WICLOUD CORPORATION) 10,490 Reputation points Microsoft External Staff Moderator

2026-01-22T02:29:23.5566667+00:00

Hi @Luigi De Giacomo ,

If you have a lot of questions, I suggest you create a new post for each question on this platform so I can support you better.

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Jack Dang (WICLOUD CORPORATION) 10,490 Reputation points Microsoft External Staff Moderator

2026-01-22T02:29:23.5566667+00:00

Hi @Luigi De Giacomo ,

If you have a lot of questions, I suggest you create a new post for each question on this platform so I can support you better.

Answer 1

Hi @Arthur P ,

Thanks for reaching out.

If you had a working InvokeDotNet method in your MAUI 9 project, it likely came from a JS helper file that you (or the sample you were following) included manually. In MAUI 10, the sample project (HybridWebView Sample) does not provide a “new” or updated JS file, because the framework expects developers to supply their own JS files as part of the app’s web assets.

In practice, when you include your web content in MAUI 10, you typically reference a JS file like this:

<script src="_framework/hybridwebview.js"></script>

This _framework/hybridwebview.js is generated when your web content is served via MAUI and handles JS-to-.NET calls. So the InvokeDotNet method isn’t something that exists in a prebuilt, framework-supplied JS file - it’s part of your app’s web content and controlled via the JS script you include.

Summary:

The framework does not ship a built-in HybridWebView.js.
You need to include any JS helper scripts that provide InvokeDotNet functionality as part of your HTML/JS assets.
_framework/hybridwebview.js is the MAUI-generated JS bridge when serving web content, and that is what you should reference in your HTML.

Hope this helps! If my answer was helpful - kindly follow the instructions here so others with the same problem can benefit as well.

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