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XAML code displays error 'System.Object was not found'

Karl 0 Reputation points
2025-11-13T18:18:56.5033333+00:00

XAML error

I have installed VS 2026 und created a new WPF Test Application.

The XAML code displays initially an error 'System.Object' was not found.

This goes away after a short while but it still worries me.

Can you explain what is going on?

Windows development | WinUI

1 answer

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  1. Michael Le (WICLOUD CORPORATION) 6,420 Reputation points Microsoft External Staff Moderator
    2025-11-14T06:31:35.0166667+00:00

    Hello @Karl ,

    Don't worry about it. When you first open a new WPF project, the designer is still loading things in the background.

    During this loading, it might briefly say it can't find basic items like System.Object.

    Once everything finishes loading, the designer finds what it needs and the error goes away.

    This happens to many developers and has been around for years. If the error disappears quickly and doesn't stop you from building or running your app, you can safely ignore it.

    I hope this clarifies things for you.

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