Why does Visual Studio 2010 randomly alter the project files for web.configs? [duplicate]

This question already has answers here: <Subtype>Designer</Subtype> Added then removed by Visual Studio on load/unload (6 answers) Closed 3 years ago.

Why does Visual Studio 2010 randomly alter the project files for web.configs?

Using Mercurial I frequently see in commit windows diffs that are

-    <Content Include="Admin\Web.config" />

+    <Content Include="Admin\Web.config">
+      <SubType>Designer</SubType>
+    </开发者_如何转开发Content>

That it will constantly flip the sub types to exist or not exist.

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I've had the same problem on occasion, it occurs for some projects, but not others. It's infuriating.

I haven't figured out the root cause, but I solved this issue by manually inserting the SubType as an attribute.

<Content Include="Admin\Web.config" SubType="Designer" />

It's a hack, but gets rid of the issue, at least in VS2008.