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Document System.Drawing OutOfMemoryException to ExternalException breaking change for .NET 10 with C# and VB examples #47939

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merged 6 commits into from
Aug 19, 2025
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Document System.Drawing OutOfMemoryException to ExternalException breaking change for .NET 10 with C# and VB examples #47939

merged 6 commits into from
Aug 19, 2025
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@Copilot Copilot AI commented Aug 12, 2025 •
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This PR adds documentation for a breaking change in .NET 10 Preview 5 where System.Drawing's GDI+ error handling was updated to throw ExternalException instead of OutOfMemoryException for Status.OutOfMemory errors.

Changes Made

Added new breaking change document: docs/core/compatibility/windows-forms/10.0/system-drawing-outofmemory-externalexception.md

  • Documents the version introduced (.NET 10 Preview 5)
  • Explains previous vs new behavior with GDI+ error handling
  • Provides reasoning: GDI+ often returns Status.OutOfMemory for invalid input rather than actual memory issues, causing confusion
  • Includes recommended action with code examples in both C# and VB.NET showing how to catch both exception types using tab groups
  • Lists affected System.Drawing APIs that use GDI+ internally
  • Updated metadata to specify both C# and VB languages are covered

Updated main compatibility index: docs/core/compatibility/10.0.md

  • Added entry to Windows Forms table in correct alphabetical order

Updated table of contents: docs/core/compatibility/toc.yml

  • Added navigation entry under Windows Forms section

Background

GDI+ isn't particularly good at returning errors when it's unable to create internal objects. Many cases where object creation fails due to invalid input result in higher-level code getting a null and turning it into Status.OutOfMemory. This change to ExternalException provides more accurate error reporting since this exception type is already used in other System.Drawing code paths for similar GDI+ errors.

The documentation follows established patterns and includes proper cross-references, code examples in both languages, and comprehensive coverage of affected APIs.

Fixes #46057.

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Internal previews

📄 File 🔗 Preview link
docs/core/compatibility/10.0.md Breaking changes in .NET 10
docs/core/compatibility/toc.yml docs/core/compatibility/toc
docs/core/compatibility/windows-forms/10.0/system-drawing-outofmemory-externalexception.md System.Drawing OutOfMemoryException changed to ExternalException

@Copilot @adegeo
Add System.Drawing OutOfMemoryException breaking change documentation…
bbdd2a8 
… for .NET 10

Co-authored-by: adegeo <67293991+adegeo@users.noreply.github.com>
@Copilot Copilot AI changed the title [WIP] [Breaking change]: System.Drawing OutOfMemoryException changed to ExternalException Document System.Drawing OutOfMemoryException to ExternalException breaking change for .NET 10 Aug 12, 2025
Copilot finished work on behalf of adegeo August 12, 2025 21:33
@Copilot Copilot AI requested a review from adegeo August 12, 2025 21:33
@Copilot @adegeo
Move System.Drawing breaking change from core-libraries to windows-forms
ca13bcf 
Co-authored-by: adegeo <67293991+adegeo@users.noreply.github.com>
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PoliCheck Scan Report

The following report lists PoliCheck issues in PR files. Before you merge the PR, you must fix all severity-1 issues. Other issues are also a high priority. The AI Review Details column lists suggestions for either removing or replacing the terms. If you find a false positive result, mention it in a PR comment and include this text: #policheck-false-positive. This feedback helps reduce false positives in future scans.

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Copilot finished work on behalf of adegeo August 14, 2025 18:20
@adegeo adegeo requested a review from gewarren August 14, 2025 19:40
@Copilot @adegeo
Add VB.NET example and language metadata for System.Drawing breaking …
24cf26f 
…change

Co-authored-by: adegeo <67293991+adegeo@users.noreply.github.com>
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PoliCheck Scan Report

The following report lists PoliCheck issues in PR files. Before you merge the PR, you must fix all severity-1 issues. Other issues are also a high priority. The AI Review Details column lists suggestions for either removing or replacing the terms. If you find a false positive result, mention it in a PR comment and include this text: #policheck-false-positive. This feedback helps reduce false positives in future scans.

✅ No issues found

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Information: PoliCheck | Severity Guidance | Term
For any questions: Try searching the learn.microsoft.com contributor guides or post your question in the Learn support channel.

@Copilot Copilot AI changed the title Document System.Drawing OutOfMemoryException to ExternalException breaking change for .NET 10 Document System.Drawing OutOfMemoryException to ExternalException breaking change for .NET 10 with C# and VB examples Aug 14, 2025
@Copilot Copilot AI requested a review from adegeo August 14, 2025 19:56
Copilot finished work on behalf of adegeo August 14, 2025 19:56
@Copilot @adegeo
Remove tab structure from code examples, let metadata handle rendering
1a6989c 
Co-authored-by: adegeo <67293991+adegeo@users.noreply.github.com>
@Copilot Copilot AI requested a review from adegeo August 14, 2025 20:11
Copilot finished work on behalf of adegeo August 14, 2025 20:11
@learn-build-service-prod Learn Build Service (PROD)
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PoliCheck Scan Report

The following report lists PoliCheck issues in PR files. Before you merge the PR, you must fix all severity-1 issues. Other issues are also a high priority. The AI Review Details column lists suggestions for either removing or replacing the terms. If you find a false positive result, mention it in a PR comment and include this text: #policheck-false-positive. This feedback helps reduce false positives in future scans.

✅ No issues found

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For any questions: Try searching the learn.microsoft.com contributor guides or post your question in the Learn support channel.

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adegeo commented Aug 14, 2025

@gewarren This is ready

@adegeo adegeo marked this pull request as ready for review August 14, 2025 20:20
@adegeo adegeo requested a review from a team as a code owner August 14, 2025 20:20
@adegeo @gewarren
Update docs/core/compatibility/windows-forms/10.0/system-drawing-outo…
4fbf2ed 
…fmemory-externalexception.md

Co-authored-by: Genevieve Warren <24882762+gewarren@users.noreply.github.com>
@adegeo adegeo enabled auto-merge (squash) August 19, 2025 14:35
@adegeo adegeo merged commit 6954c15 into main Aug 19, 2025
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@adegeo adegeo deleted the copilot/fix-46057 branch August 19, 2025 14:37
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[Breaking change]: System.Drawing OutOfMemoryException changed to ExternalException
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