---
name: .NET Core breaking change
about: Report a change in .NET Core that breaks something that worked in a previous version (intended mostly for product-team use)
---

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This issue template is for use in creating issues that document breaking changes. This template can be used to create an issue:

- By Microsoft product team members who are documenting a breaking change.

- By Microsoft customers who are experiencing a compatibility issue between .NET Framework and .NET Core or between versions of .NET Core.

Text in brackets is a placeholder; replace the text with the requested information and remove the brackets before submitting the issue.

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## [Change title]

[Brief description of the change]

### Version introduced

[Version in which the breaking change first occurred (for example, 3.0 for .NET Core 3.0)]

### Old behavior

### New behavior

### Reason for change

### Recommended action

[ Suggested steps if user is affected go here:
- Possible workarounds
- Example of code changes to handle change
]

### Category

[Choose a category from one of the following:

- ASP.NET Core
- C#
- Core .NET libraries
- Cryptography
- Data
- Debugger
- Deployment
- Globalization
- Interop
- JIT
- LINQ
- Managed Extensibility Framework (MEF)
- MSBuild
- Networking
- Printing
- Security
- Serialization
- Visual Basic
- Windows Forms
- Windows Presentation Foundation (WPF)
- XML, XSLT
]

### Affected APIs

[ If no APIs are affected, this should read:
     "Not detectable via API analysis"

  If affected APIs are identifiable, include a link for each. The link takes the form:

  `[friendly description of API](link to API on docs.microsoft.com)`

  For example, `[String.IndexOf(String)](https://docs.microsoft.com/dotnet/api/system.string.indexof#System_String_IndexOf_System_String_)

  For methods, if all overloads are affected, link to the general overloaded method page. For example:

  <https://docs.microsoft.com/dotnet/api/system.string.indexof>

  Otherwise, link to the individual method overload. For example:

  <https://docs.microsoft.com/dotnet/api/system.string.indexof#System_String_IndexOf_System_String_>

]

<!-- Do not modify anything below this line -->

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#### Issue metadata

* Issue type: breaking-change