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Wait, My Custom Characters Turned Into Gibberish! The Windows 11 / Server 2025 Bug Is Already Fixed

JP Windows Support ★★ View Markdown
#microsoft#infrastructure

Hey there, it's me, Shiichan! Today isn't the usual shiny-new-feature story, it's a rarer one: a character-rendering bug. It might sound minor, but it's a real headache if your systems rely on custom (EUDC) characters.

JP Windows Support jpwinsup.github.io

What was announced?

JP Windows Support, the blog run by Microsoft Japan's Windows support team, published a post about a bug affecting Windows 11 (version 24H2 / 25H2) and Windows Server 2025: EUDC (End-User Defined Character) glyphs registered in the Unicode Private Use Area (PUA) could fail to display or print correctly, along with how to fix it.

The story so far

On systems that installed updates released from September 2025 onward, EUDC characters registered in certain code ranges could show up as a different character or symbol instead of the one that was actually registered. The affected Unicode code ranges are:

  • U+E76C
  • U+E78D - U+E796
  • U+E7C7 - U+E7C8
  • U+E7E7 - U+E7F3
  • U+E815 - U+E864

This affected Windows 11 version 24H2 / 25H2 and Windows Server 2025, on systems whose OS build number (checked via winver) fell within a specific range.

What changes

Good news: an update that fixes this bug is already available. If you're an admin running business systems, forms, or printing workflows that rely on EUDC characters, it's worth checking whether your build falls in the affected range and installing the fix if so. If you keep up with Windows Update regularly, there's a good chance you're already patched.

Dive Deep

Here are the exact affected build ranges and the updates that resolve them.

Affected build numbers (check with winver)

  • Windows 11, version 24H2: 26100.4484 or later, before 26100.8328
  • Windows 11, version 25H2: 26200.6584 or later, before 26200.8328
  • Windows Server 2025: 26100.6584 or later, before 26100.33296

Updates that include the fix

  • Windows 11 (24H2/25H2): the preview update KB5083631 released April 30, 2026 (OS builds 26200.8328 / 26100.8328), or KB5089549 released May 12, 2026 (OS builds 26200.8457 / 26100.8457) or later
  • Windows Server 2025: KB5120233 released August 11, 2026 (OS build 26100.33296) or later

Installing an update at or after these builds resolves the issue. If you've paused Windows Update or intentionally run an older build, that's worth double-checking.

Wrap-up

  • Windows 11 (24H2/25H2) and Windows Server 2025 had a bug causing EUDC (custom) characters to display or print incorrectly
  • The cause was updates released from September 2025 onward, which could replace EUDC characters in specific Unicode (PUA) ranges with the wrong glyph
  • Windows 11 is fixed by the April or May 2026 update; Windows Server 2025 is fixed by the August 2026 update
  • If you run business systems or forms that rely on custom characters, check your build number with winver and confirm you're up to date

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