Build 26120.1252: Windows Insider Dev Channel, July 2024. Lock screen cards and easier app pinning

Build 26120.1252 for the Dev Channel starts rolling out lock screen content and lets you drag Start menu apps to the taskbar. It also includes fixes and lists several known issues.

Does it affect you? Applies to: Devices enrolled in the Windows Insider Program in the Dev Channel.

Review notes Additional details from the official release notes (3) Read notes

In detail The “(repair version)” notice applies to Windows Insiders joining the Dev Channel from PCs running Windows 11, version 24H2 Build 26100.xxxx. It means an in-place upgrade will update the PC to the latest Dev Channel build.
In detail Windows Sandbox will fail to launch with error 0x80370106.
What changes Windows Sandbox will fail to launch with error 0x80370106. The update also fixes an underlying issue believed to cause that error.

The official sources are linked at the end of the page.

This is a test build for people in the Windows Insider Program. Features in it can change, be removed, or never reach regular Windows releases.

What changes

Fixes 11 changes

File Explorer

Gradual rollout

For: Insiders with the latest-updates toggle on

File Explorer no longer crashes when you navigate away from Home.¹
Fixes an issue that could make explorer.exe crash when navigating away from Home.

Input

Gradual rollout 2 items

Pinyin no longer appears twice in the list of available input methods during Windows Setup.²
Fixes a duplicate Pinyin entry during Windows Setup (OOBE).
A cyclical input crash that affected a small number of Insiders in the previous build is fixed.⁷
The crash affected various input experiences.

Windows Sandbox

Gradual rollout

For: Insiders with the latest-updates toggle on

A suspected cause of error 0x80370106 when launching Windows Sandbox is fixed, although the post still lists Sandbox launch failure as a known issue.³
Fixes an underlying issue believed to cause error 0x80370106 when launching Windows Sandbox.

Volume Mixer

Gradual rollout

For: Insiders with the latest-updates toggle on

Microsoft Edge's preferred volume setting now persists when you restart the app.⁴
Fixes an issue with the preferred audio volume for Microsoft Edge under Settings > System > Sound > Volume Mixer.

General

For: Everyone in the Dev Channel

Some Insiders no longer see a KERNEL_SECURITY_CHECK_FAILURE error that causes a bugcheck.⁵

Animations

For: Everyone in the Dev Channel

Some animations, particularly in Task View, no longer stutter or drop frames.⁶

Input Method Editor

For: Everyone in the Dev Channel

The candidate list no longer fails to appear or appear in the wrong position.⁸
Fixes an issue with the Input Method Editor (IME) candidate list.

Voice Typing

For: Everyone in the Dev Channel

Voice Typing no longer returns errors with certain languages, such as Chinese.⁹

Settings

For: Everyone in the Dev Channel

The slow-charger warning no longer shows duplicate text under Power & Battery.¹⁰
Fixes duplicate text in Settings > System > Power & Battery when showing a warning about a slow charger.

Pcasvc.dll

For: Everyone in the Dev Channel

Some people upgrading from Windows 11, version 22H2 or 23H2 to a 26xxx build no longer see a missing-entry error dialog.¹¹
Fixes the underlying issue causing a Pcasvc.dll dialog with the message “Missing entry: PcaWallpaperAppDetect”.

New features 7 changes

Start menu

Gradual rollout

For: Insiders with the latest-updates toggle on

Drag an app from the pinned section of the Start menu to the taskbar to pin it there.¹²

File Explorer

Gradual rollout

For: Insiders with the latest-updates toggle on

You can drag and drop files between breadcrumb sections in the File Explorer address bar.¹³

Lock screen

Gradual rollout

For: Insiders with the latest-updates toggle on

The lock screen is starting to show finance, traffic, and sports updates alongside weather. The cards also have updated sizing, spacing, fonts, and a blurred background.¹⁴

Paint

Gradual rollout 2 items

For: Insiders in the Canary and Dev Channels

With a supported stylus, press its eraser button or flip it around to switch to the eraser in Paint.¹⁵
The Paint update is version 11.2406.34.0 or newer.
Use the stylus side button while hovering over the canvas to select an area with the free-form selection tool.¹⁶
The Paint update is version 11.2406.34.0 or newer.

Microsoft Store

Gradual rollout 2 items

The Store search box can show suggested content in a new panel below the search display.¹⁷
Available with Microsoft Store version 22406.xxxx.x and higher.
The Gaming page lets you browse game categories such as strategy, role-playing, shooter, sport, puzzle, and simulation.¹⁸
The category browsing trial is available in the US, UK, and Canada.

Improvements 5 changes

Servicing technology

For: Insiders in the Dev Channel

This update uses a format that previews servicing technology enhancements for Windows 11, version 24H2.¹⁹

General

Gradual rollout

For: Insiders with the latest-updates toggle on

A set of features whose rollout was paused is starting to roll out again, initially to a small share of Insiders. Individual features may arrive at different times.²⁰

Widgets

Gradual rollout

For: Insiders with the latest-updates toggle on

Taskbar icons for Widgets are clearer, and a larger set of animated icons is rolling out.²¹

Taskbar

For: Everyone in the Dev Channel

Flashing app icons are easier to see on the taskbar.²²

Mobile operators

For: Everyone in the Dev Channel

Mobile operator settings profiles are updated for certain operators.²³
Updates Country and Operator Settings Asset (COSA) profiles for certain mobile operators.

Technical details

Data sheet · Security · Downloads · Components Click to collapse or expand

Data sheet

Released: 2024-07-15
Type: Windows Insider build

Version	Build	Channel
—	26120.1252	Dev Channel

Security

No vulnerabilities are listed for this update.

Sources

Windows Insider Blog

Updated Oct 27, 2026

Cited passages from Microsoft's official notes (23)

1. Fixed an issue which could make explorer.exe crash when navigating away from Home. blogs.windows.com
2. Fixed an issue where if you went through Windows Setup (OOBE), pinyin would be unexpectedly displayed twice in the list of available input methods. blogs.windows.com
3. Fixed an underlying issue believed to be the cause of Insiders seeing error 0x80370106 when trying to launch Windows Sandbox after the latest flights. blogs.windows.com
4. Fixed an issue which was causing the preferred audio volume (under Settings > System > Sound > Volume Mixer) for Microsoft Edge to not persist across restarting the app. blogs.windows.com
5. Fixed an issue causing some Insiders to see a bugcheck with error KERNEL_SECURITY_CHECK_FAILURE in recent flights. blogs.windows.com
6. Fixed an issue believed to be the underlying cause of some Insiders noticing stutters in some animations recently (dropping frames), particularly with Task View. blogs.windows.com
7. Fixed an issue causing a cyclical input crash in the previous flight for a small number of Insiders, which impacted various input experiences. blogs.windows.com
8. Fixed an issue where the Input Method Editor (IME) candidate list may fail to show or showed in the wrong position. blogs.windows.com
9. Fixed an issue causing Insiders to see errors when attempting to use Voice Typing with certain languages such as Chinese. blogs.windows.com
10. Fixed an issue where Settings > System > Power & Battery unexpectedly had duplicate text when showing a warning about a slow charger. blogs.windows.com
11. Fixed the underlying issue causing some Insiders to see a Pcasvc.dll error dialog pop-up with the message “Missing entry: PcaWallpaperAppDetect” after upgrading from Windows 11, version 22H2/23H2 to a 26xxx build. blogs.windows.com
12. You can now also pin apps from the Start menu to the taskbar by dragging and dropping items directly to taskbar from the pinned section in the Start menu. blogs.windows.com
13. Drag-and-drop files with your mouse functionality between breadcrumbs is now available in the File Explorer Address Bar blogs.windows.com
14. Stay informed and efficient with dynamic updates that bring finance, traffic, and sports to your Lock screen, alongside weather. blogs.windows.com
15. users can now seamlessly switch from their current tool to erase by pressing on the eraser button or flipping to the back of the stylus pen to erase. blogs.windows.com
16. users can click on the side button when they hover the stylus pen over the screen to use the free-form selection tool and select anything on the canvas quickly. blogs.windows.com
17. When you’re searching for content in the Store Search box, a new flyout at the bottom of the search display suggests content you may be interested in. blogs.windows.com
18. From the Gaming page, you can now navigate easily and quickly through different game categories such as strategy, role-playing, shooter, sport, puzzle, and simulation. blogs.windows.com
19. This update is delivered in a format that offers a preview of enhancements to servicing technology on Windows 11, version 24H2. blogs.windows.com
20. We are beginning to enable again the set of new features we started to enable on 6/28 but paused on 6/30. blogs.windows.com
21. We are also making some improvements to the Widgets button on the taskbar so that the icons on the taskbar are clearer and we are rolling out a larger set of animated icons too. blogs.windows.com
22. Updated the app icon flashing in the taskbar to be a bit easier to see. blogs.windows.com
23. This update brings Country and Operator Settings Asset (COSA) profiles up to date for certain mobile operators. blogs.windows.com

Checked automatically: 8 of 8 checks passed, 23 quoted passages

Quotes found in the official pages: passed
Numbers found in the sources: passed
Vulnerabilities from the dossier only: passed
Links to allowed domains only: passed
Every official change covered: passed
Readable plain text: passed
Changes confirmed by the file list: passed
Sources agree: passed

A second AI read the text against the sources: correctness 3/5, clarity 4/5, completeness 5/5. How we work

Published by The Update Bureau. Written with AI from Microsoft's own documents, checked by rules and a second AI. How we work · Report a mistake