Add known issue to 08-11-august-cumulative-update.md

[TaraOverfield]

Summary

Add two WPF known issues to the release notes.

Fixes #Issue_Number (if available)

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Internal previews

File	Preview link
docs/framework/release-notes/2026/08-11-august-cumulative-update.md	Learn preview

Build report

[Copilot]

🟡 Changes recommended

The update note includes a spelling error, and several new sections use “may” where the repo’s doc style consistently prefers “might/can,” which should be corrected before merging.

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Pull request overview

Updates the .NET Framework August 2026 cumulative update release notes to document newly identified WPF known issues and their workarounds.

Changes:

• Updates the page metadata date and adds an “Updated” note under the release date.
• Replaces the “no known issues” statement with two WPF known issues, including workarounds and investigation status.

File summaries

File	Description
docs/framework/release-notes/2026/08-11-august-cumulative-update.md	Adds two WPF known issues to the August 2026 cumulative update release notes and updates page metadata accordingly.

Review details

Suppressed comments (4)

docs/framework/release-notes/2026/08-11-august-cumulative-update.md:74

• Replace "may" with "might" in the failure description to match repo style guidance (avoid "may" in docs).

After installing the August 2026 .NET Framework cumulative update, WPF applications that print—or display print preview—from an in-memory XPS document registered with `System.IO.Packaging.PackageStore` may fail with a `System.IO.FileFormatException` while the document is loading. This occurs when the package identity used as both the `PackageStore` key and the `XpsDocument` package identity is an absolute URI that uses the `pack` scheme—for example, `pack://<guid>.xps`. Images and fonts contained within the same XPS package are then incorrectly rejected as being outside the package. Application code and XPS content do not need to have changed for this failure to occur.

docs/framework/release-notes/2026/08-11-august-cumulative-update.md:89

• Replace "may" with "might" for possibility statements (avoid "may" in docs).

This switch disables security protections introduced in the August 2026 update and may increase exposure to the vulnerabilities addressed by that update. Microsoft recommends using this workaround only as a temporary measure and only when required to address this issue.

docs/framework/release-notes/2026/08-11-august-cumulative-update.md:66

• Replace "may" with "might" for possibility statements (avoid "may" in docs).

This switch disables security protections introduced in the August 2026 update and may increase exposure to the vulnerabilities addressed by that update. Microsoft recommends using this workaround only as a temporary measure and only when required to address this issue.

docs/framework/release-notes/2026/08-11-august-cumulative-update.md:72

• Use sentence case for headings; "Known Issue" should be "Known issue" to match the rest of the document's heading style.

#### Known Issue

• Files reviewed: 1/1 changed files
• Comments generated: 3
• Review effort level: Lite

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[TaraOverfield]

@mairaw or @adegeo can you review/approve this PR to merge known issue?

[mairaw]

Approving but some sections I'd rewrite to remove the usage of —
it looks like AI text and could be rewritten in an easier way to parse