Clarify .NET Framework 4.x versioning in side-by-side installation docs

[Copilot]

Summary

The documentation incorrectly stated that only one version of .NET Framework can exist on a machine. This is misleading—multiple .NET Framework major versions (3.5 and 4.x) can coexist, but only one 4.x version can be installed at a time.

Changes:

• Specified that the side-by-side limitation applies to .NET Framework 4.x specifically
• Added parenthetical note that .NET Framework 3.5 is separate and optional

Before:

Side-by-side installation isn't possible with .NET Framework. It's a Windows component, and only one version can exist on a machine at a time...

After:

Side-by-side installation isn't possible with .NET Framework 4.x. It's a Windows component, and only one version of .NET Framework 4.x can exist on a machine at a time (.NET Framework 3.5 is separate and optional)...

Fixes #49862

Original prompt

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This section details on the original issue you should resolve

<issue_title>More than one version of .NET Framework can be installed on a Windows PC</issue_title>
<issue_description>### Type of issue

Typo

Description

The documentation states the following, "Side-by-side installation isn't possible with .NET Framework. It's a Windows component, and only one version can exist on a machine at a time: each version of .NET Framework replaces the previous version. If you install a new app that targets a later version of .NET Framework, you might break existing apps that run on the machine because the previous version was replaced."

This seems incorrect. I have installed multiple versions of .NET Framework on a Windows PC. I think this needs to be clarified better.

Page URL

https://learn.microsoft.com/en-us/dotnet/standard/choosing-core-framework-server

Content source URL

https://github.com/dotnet/docs/blob/main/docs/standard/choosing-core-framework-server.md

Document Version Independent Id

95083e1c-ef53-e813-08e2-1aa31b431f00

Platform Id

4eaee7e4-968f-100a-bc55-d4bd576a5e5b

Article author

@gewarren

Metadata

• ID: 7b76cb0d-df6d-88c4-557d-ad327a566eef
• PlatformId: 4eaee7e4-968f-100a-bc55-d4bd576a5e5b
• Service: dotnet-fundamentals

Related Issues</issue_description>

<agent_instructions>Improve that paragraph specifying you can only have one version of .NET Framework 4 installed and add a parenthetical clause mentioning that .NET Framework 3.5 is optional but separate from .NET Framework 4.</agent_instructions>

Comments on the Issue (you are @copilot in this section)

@adegeo Yeah. I mean you can have Framework 3.5 and 4.X installed and only one version of 4.X and one version of 3.5. I don't know if it's worth clarifying? Maybe a tiny bit? Maybe copilot can just improve that paragraph with .NET Framework 3.5 as a parenetical clause.

• Fixes More than one version of .NET Framework can be installed on a Windows PC #46812

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