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I am getting HTTP Error 500.30 - ASP.NET Core app failed to start.

Eric Wilson 25 Reputation points
2026-01-19T00:08:30.5633333+00:00

I am getting an HTTP Error 500.30 - ASP.NET Core app failed to start when Publishing my Blazor application from my local Visual Studio.

I also get "System.IO.FileNotFoundException: Could not load file or assembly 'Microsoft.Extensions.DependencyInjection.Abstractions, Version=10.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60'. The system cannot find the file specified. File name: 'Microsoft.Extensions.DependencyInjection.Abstractions, Version=10.0.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60'"

Why would it run locally but needs this after I publish?

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Answer accepted by question author

Aditya N 2,975 Reputation points Microsoft External Staff Moderator
2026-01-19T02:37:19.4133333+00:00

Hello @Eric Wilson

Thank you for reaching out Microsoft Q&A. This error is mainly triggered by often triggered by misconfigurations, dependencies or environment mismatches. Please could you share your details logs.

To access these logs, go to: Event Viewer -> Windows Logs -> Application.

If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".

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