Blazor hot reload always fails with unexpected drror

[vsfeedback]

This issue has been moved from a ticket on Developer Community.

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[severity:It's more difficult to complete my work]

Every time I edit any file.

10:35:56.68 Prestwood.Integrations (Web server): Hot reload session started
10:36:00.57 Prestwood.Integrations (Web assembly): Hot reload session started
10:37:16.45 Prestwood.Integrations (Web assembly): Sending updates to running application
10:37:16.48 Prestwood.Integrations (Web assembly): [Error] Applying updates to the application failed. Web socket connection to the browser has been closed: 
10:37:16.48 An unexpected error has occurred, any pending updates have been discarded.

The browser dev tools shows two web socket connections on the network tab and this in the console.

[2025-09-29T09:43:30.610Z] Information: Connection disconnected. blazor.web.js:1:47009
[2025-09-29T09:43:35.734Z] Information: Normalizing '_blazor' to 'https://localhost:5202/_blazor'. blazor.web.js:1:47009
[2025-09-29T09:43:35.759Z] Information: WebSocket connected to wss://localhost:5202/_blazor?id=Fc2ONu9sAequYFZN1fnwKw. blazor.web.js:1:47009
The connection to wss://localhost:5202/_blazor?id=Fc2ONu9sAequYFZN1fnwKw was interrupted while the page was loading. blazor.web.js:1:81337
[2025-09-29T09:44:15.830Z] Information: (WebSockets transport) There was an error with the transport. blazor.web.js:1:47009
[2025-09-29T09:44:15.830Z] Error: Connection disconnected with error 'Error: WebSocket closed with status code: 1006 (no reason given).'. blazor.web.js:1:46926
[2025-09-29T09:44:18.845Z] Information: Normalizing '_blazor' to 'https://localhost:5202/_blazor'. blazor.web.js:1:47009
[2025-09-29T09:44:25.655Z] Warning: Error from HTTP request. TypeError: NetworkError when attempting to fetch resource.. blazor.web.js:1:46966
[2025-09-29T09:44:25.655Z] Error: Failed to complete negotiation with the server: TypeError: NetworkError when attempting to fetch resource. blazor.web.js:1:46926
[2025-09-29T09:44:25.655Z] Error: Failed to start the connection: Error: Failed to complete negotiation with the server: TypeError: NetworkError when attempting to fetch resource. blazor.web.js:1:46926
[2025-09-29T09:44:25.656Z] Error: Error: Failed to complete negotiation with the server: TypeError: NetworkError when attempting to fetch resource. blazor.web.js:1:40375
[2025-09-29T09:44:25.656Z] Error: Error: Failed to complete negotiation with the server: TypeError: NetworkError when attempting to fetch resource. blazor.web.js:1:40375
[2025-09-29T09:44:46.120Z] Information: Normalizing '_blazor' to 'https://localhost:5202/_blazor'. blazor.web.js:1:47009
[2025-09-29T09:44:53.154Z] Warning: Error from HTTP request. TypeError: NetworkError when attempting to fetch resource.. blazor.web.js:1:46966
[2025-09-29T09:44:53.155Z] Error: Failed to complete negotiation with the server: TypeError: NetworkError when attempting to fetch resource. blazor.web.js:1:46926
[2025-09-29T09:44:53.155Z] Error: Failed to start the connection: Error: Failed to complete negotiation with the server: TypeError: NetworkError when attempting to fetch resource. blazor.web.js:1:46926
[2025-09-29T09:44:53.155Z] Error: Error: Failed to complete negotiation with the server: TypeError: NetworkError when attempting to fetch resource. blazor.web.js:1:40375
[2025-09-29T09:44:53.156Z] Error: Error: Failed to complete negotiation with the server: TypeError: NetworkError when attempting to fetch resource. blazor.web.js:1:40375
[2025-09-29T09:45:13.158Z] Information: Normalizing '_blazor' to 'https://localhost:5202/_blazor'. blazor.web.js:1:47009
[2025-09-29T09:45:19.555Z] Warning: Error from HTTP request. TypeError: NetworkError when attempting to fetch resource.. blazor.web.js:1:46966
[2025-09-29T09:45:19.555Z] Error: Failed to complete negotiation with the server: TypeError: NetworkError when attempting to fetch resource. blazor.web.js:1:46926
[2025-09-29T09:45:19.555Z] Error: Failed to start the connection: Error: Failed to complete negotiation with the server: TypeError: NetworkError when attempting to fetch resource. blazor.web.js:1:46926
[2025-09-29T09:45:19.556Z] Error: Error: Failed to complete negotiation with the server: TypeError: NetworkError when attempting to fetch resource. blazor.web.js:1:40375
[2025-09-29T09:45:19.556Z] Error: Error: Failed to complete negotiation with the server: TypeError: NetworkError when attempting to fetch resource. blazor.web.js:1:40375
[2025-09-29T09:45:41.208Z] Information: Normalizing '_blazor' to 'https://localhost:5202/_blazor'. blazor.web.js:1:47009

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[javiercn]

Thanks for contacting us.

Can you capture additional details about the issue, like the debug logs for hot reload from visual studio?

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