Microsoft has rolled out Windows 11 Insider Preview Build 26220.7523 (KB5072043) to the Dev and Beta channels, and with it comes a targeted set of repairs for one of the more visible and annoying regressions from recent preview flights: the jarring white flash in File Explorer when using dark mode. That single visual glitch — which repeatedly made headlines and spurred user outcry — is now listed as fixed in the official Insider release notes, alongside improvements to File Explorer search reliability, a RemoteApp/OneDrive file-opening fix, and modest but important accessibility updates for Voice Access in Gallery view.
Background: how a UI polish became a flash problem
Microsoft shipped a preview update in early December intended to expand dark mode consistency across File Explorer and its dialog UIs. The intent was straightforward: bring legacy file-operation dialogs and related chrome into alignment with the system dark theme so low‑light workflows would be less visually jarring. Instead, a rendering regression appeared for some systems: when opening File Explorer or switching between certain Explorer pages, the window could briefly paint as a blank white surface before redrawing in dark mode. The symptom was widespread enough to be documented by Microsoft and covered extensively by mainstream tech outlets. That initial regression was tracked to the preview package labeled KB5070311 (builds in the 26200 series for 25H2). Microsoft acknowledged the problem and listed it as a known issue while work on a fix proceeded. The white-flash behavior quickly became the most visible quality concern from the December preview rollout because it affected a core, frequently used shell experience and clashed with the stated goal of improving dark visuals. Independent outlets reproduced the symptom and reported on how it impacted users, especially those using dark mode on bright or high-contrast displays. In response, Microsoft shipped the December 9 cumulative update (KB5072033) for supported channel devices; its release notes list the white‑flash regression as addressed for affected builds. Insiders and some general-release users saw improvements after KB5072033, but the issue kept drawing attention as Microsoft iterated on the fix and folded similar changes back into Insider channels for verification and fine-tuning.
What KB5072043 changes — a close look at the fixes
File Explorer white‑flash fix
- What Microsoft says: the Insider release notes explicitly state they “Fixed an issue causing File Explorer recently to show a white flash when navigating between pages after the latest flights.” This is the same visual regression users had been seeing after earlier preview builds.
- Why it matters: the white flash was more than cosmetic for many users; when you rely on dark mode, an abrupt white repaint is visually uncomfortable and undermines user confidence in the update quality process. Fixing it restores the promised visual consistency and reduces the risk of eye strain or momentary disorientation in low‑light contexts.
- What’s still unknown: Microsoft’s public notes do not provide granular technical detail about the root cause. Community analysis and posts indicate the problem likely stemmed from timing between legacy Win32 UI painting and the dark-theme repaint, producing a transient light background. That community diagnosis is plausible but not formally confirmed by Microsoft — treat the hypothesis as informed speculation until an engineering postmortem is published.
Search performance and indexing improvements
- What Microsoft updated: the build “made some improvements to File Explorer search performance by eliminating duplicate file indexing operations,” and also “enhanced search reliability with improved handling of system and secondary drive locations.” In short, Microsoft says it removed redundant indexing work and improved how the search engine treats files on additional storage.
- Practical effect: removing duplicate indexing should reduce background CPU/disk I/O and speed search queries, especially on machines with slower storage or large multi-drive setups. Users who reported delayed search results, excessive indexing activity, or intermittent high disk usage during file operations may see measurable improvements.
- Caveats: the Insider notes describe an improvement, not a guarantee. Because search behavior depends on index state, file count, and third‑party storage drivers or services (for example, cloud-sync filters), real‑world gains will vary. Enterprises with complex storage topologies should test before assuming uniform latency reductions.
OneDrive in RemoteApp: 0x80070057 resolved
- The problem: a subset of RemoteApp scenarios could fail when attempting to open OneDrive files, producing error 0x80070057. RemoteApp environments and virtual desktop infrastructure commonly depend on seamless cloud file access, so this was a practical blocker for affected configurations.
- The fix: KB5072043 lists a targeted correction: OneDrive files that previously failed to open in RemoteApp sessions now open properly, removing the 0x80070057 condition. This should help admins who rely on RemoteApp or multi-session deployments that surface OneDrive content in the host session.
Voice Access in File Explorer’s Gallery view
- Accessibility tweak: Voice Access gained a small but meaningful behavior change: you can open photos in Gallery by saying “click [number]” rather than needing the "double click" command. That nuance improves discoverability and reduces the cognitive burden on users who rely on voice navigation. For users with limited dexterity, this simplification is a real usability win.
Why the fixes show progress — and why caution remains
Strengths of the release
- Targeted, user-visible repairs: The white‑flash fix is precisely the kind of "annoyance that should never have left preview" but is also low-risk to validate; shipping it to Insiders for confirmation follows a sound rollout strategy. KB5072043 bundles practical fixes rather than sweeping new features, which is appropriate for a stabilization flight.
- Real-world performance tuning: Eliminating duplicate indexing operations addresses a measurable cause of high system load during file operations. This is meaningful for users with large catalogs or slower drives, where I/O contention turns into noticeable search lag.
- Accessibility attention: The Voice Access change is small but emblematic — Microsoft continues to iterate on spoken-command ergonomics across shell experiences, and making simple voice instructions behave more naturally benefits a segment of users who are too often overlooked.
Risks and limitations
- Staged rollouts and fragmentation: Microsoft’s fixes are being shipped through multiple channels (preview, cumulative, Insider toggles), which can create inconsistent experiences across user systems. KB5072033 (the December 9 cumulative) already listed a fix for the white flash, but KB5072043 brings the same repair and additional improvements into the Insider 26220-series build. That fragmentation is standard for Windows servicing, but it can confuse users about whether they already have a fix or still need to install an Insider build.
- New issues can follow fixes: the Insider release notes explicitly list remaining File Explorer issues — missing scrollbar/footer artifacts in scaled dark-mode copy dialogs and a context‑menu crash for some Insiders — meaning Explorer is still a fragile area in some configurations. Insiders should test carefully before adopting this build on primary machines.
- Limited public technical disclosure: Microsoft’s notes describe symptom-level fixes but rarely reveal engineering root causes or regression timelines. That’s understandable from a support perspective, but it limits the community’s ability to validate long-term stability improvements or to learn deeper lessons about the code paths affected.
How this affects different user groups
For Windows Insiders (Dev & Beta)
- If you're in Dev or Beta, KB5072043 will appear as Build 26220.7523. The blog post makes clear both channels are receiving this build for the 25H2 branch while Microsoft holds them the same number — a temporary alignment intended to let Dev users switch to Beta if they prefer more conservative updates. Insiders who want the fix and are comfortable with preview builds can install and provide feedback.
- Keep in mind known issues in the release notes. Test File Explorer scenarios (dark-mode navigation, context menu operations, copy dialogs) after upgrading and report any regressions through Feedback Hub.
For general-release users (non-Insiders)
- If you’re on the regular release track and experienced the white-flash regression after the December preview, there’s reason to expect relief: the December 9 cumulative update (KB5072033) included a File Explorer flash fix for affected builds, so applying that security/cumulative update is the right first step. Enterprises and admins should validate KB5072033 in their environment and check for staged rollout indicators.
- Non-Insider users should generally avoid joining the Dev channel just to get a fix, unless they have non-critical test hardware. Rolling into Insider flights risks exposure to other active experiments and regressions.
For enterprise admins and IT pros
- RemoteApp/OneDrive scenario owners should verify the OneDrive/RemoteApp fix for 0x80070057 by reproducing prior failure cases in a test collection of session hosts and Remote Desktop Services configurations. If your environment had this exact error, the Insider note indicates remediation is available, but confirm in a controlled test before pushing to production.
- Search and indexing behavior matters in managed environments. Eliminating duplicate indexing runs is beneficial, but admins with custom index paths, third-party filters, or networked storage should monitor indexing health and query latency following the update.
Practical upgrade guidance (recommended steps)
- Check Windows Update: open Settings > Windows Update and see if KB5072033 or KB5072043 is offered for your device. Install cumulative fixes before exploring Insider flights if you’re on production hardware.
- For Insiders: open Settings > Windows Update > Windows Insider Program to confirm you’re in the Dev or Beta channel and that the build number shown is 26220.7523 if you want the latest Insider fixes.
- Test File Explorer scenarios after updating: use dark mode, open and switch pages, toggle the Details pane, and create new tabs to confirm the white-flash symptom is resolved on your device.
- Validate OneDrive/RemoteApp behavior if applicable: reproduce the previous 0x80070057 condition in a controlled test before broader deployment.
- Report regressions: use Feedback Hub (WIN + F) to file reproducible bugs including repro steps, machine configuration, and whether the issue appears after a clean boot or with safe-mode drivers disabled.
Deeper analysis: what this sequence reveals about Microsoft’s release process
Microsoft’s public handling of the File Explorer white‑flash regression spotlights two dynamics that will matter to Windows power users and IT teams in the months ahead.
- First, the company is balancing feature expansion (more complete dark mode coverage, Copilot integrations, OneDrive UX changes) with the reality that many core subsystems are legacy Win32 components that must be layered into modern WinUI and dark-theme rules. Those integration points are delicate; changing paint timing or theme initialization across old and new code can expose transient visual regressions. Community discussion and forum posts point at that interplay as the most likely origin for the flash, though the company has not published a full postmortem.
- Second, Microsoft’s cadence — preview flights, cumulative fixes, and Insider builds — aims to accelerate fixes but also produces a complex map of who receives a repair and when. KB5072033’s December 9 rollup addressed the flash for many users, while KB5072043 reintroduces the fix into the 26220 Insider line and augments it with search and accessibility tweaks. This stepwise approach helps validate behavior across system permutations, but it also means end users must pay attention to KB numbers and build series to know whether a machine is fully patched.
- Third, the public communications model remains symptom-centric. Microsoft’s release notes reliably tell you that something is "fixed," but they rarely provide a technical breakdown of the underlying bug or a timeline for regression roots. This limits how much the ecosystem can learn from each incident and complicates third-party driver and app vendor troubleshooting.
What to watch next
- Monitoring staged rollouts: features and fixes continue to be staged. If you don’t see the behavior change immediately after installing a cumulative or Insider patch, it may simply be phased; wait 24–72 hours and confirm telemetry if you manage multiple machines.
- Feedback and telemetry: keep an eye on Feedback Hub and community forums for reports of residual white‑flash symptoms or new Explorer regressions. Known issues in the Insider notes show Microsoft is closely tracking a small set of remaining Explorer problems.
- Patch consolidation: Microsoft will likely fold the Insider validations into future cumulative releases. Admins should expect subsequent Patch Tuesdays to consolidate fixes, but continue to follow KB release notes to identify which package contains each repair.
Conclusion
KB5072043 (Build 26220.7523) is a focused Insider flight that delivers pragmatic, user-facing fixes for File Explorer and its search subsystem, patches a specific OneDrive in RemoteApp failure, and tightens accessibility in Gallery voice commands. The white‑flash regression that dominated coverage after early December preview builds is listed as resolved in this release — an important win for user experience in dark mode — and the indexing improvements promise tangible gains for search performance across system and secondary drives. At the same time, the sequence of preview, cumulative, and Insider updates highlights an ongoing tension: expanding features into legacy subsystems can produce highly visible regressions, and Microsoft’s staged fix model means multiple KBs and build numbers will be involved before fixes are universally available. Users on production machines should prefer cumulative security updates (such as KB5072033) and avoid jumping channels unless they have test systems; Insiders should validate the fixes and continue to report any regressions. The visible progress is encouraging, but the Explorer story is also a reminder that even small visual regressions can erode user trust — and they’re worth fixing properly.
Source: Windows Report
Microsoft Finally Fixes File Explorer's Jarring White Flash Issue With KB5072043 Update