Windows 11 Preview Updates Trigger File Explorer Flashes and Lock Screen Glitch

A recent pair of Windows 11 preview updates is causing some unwelcome visual glitches for certain users. After installing the optional releases, people are reporting bright white flashes in File Explorer when using dark mode and a disappearing password icon on the lock screen. The underlying features still work, but the UI bugs can be jarring and confusing. Microsoft has acknowledged both issues and is working on a fix, but for now the main options are to uninstall the updates or use simple workarounds.

Quick Summary

• File Explorer in dark mode can briefly flash a bright white screen after installing the December 1, 2025 preview update KB5070311 on Windows 11.
• The password sign-in icon on the lock screen can go invisible after the August 2025 non-security preview KB5064081 or any later update, including KB5070311.
• Microsoft has acknowledged both issues as known bugs and says it’s working on fixes, but there is no confirmed patch date yet.

What’s Actually Happening in File Explorer

The File Explorer issue comes from the optional November 2025 preview update KB5070311, released on December 1, 2025 for Windows 11 24H2 and 25H2.

After you install KB5070311 and use dark mode, File Explorer may:

• briefly show a blank white screen when you open it
• flash white when you:
  • switch between Home and Gallery
  • create a new tab
  • turn the Details pane on or off
  • choose More details in file copy dialogs

This is a regression Microsoft explicitly lists under “File Explorer might flash with a white screen in dark mode” in the official KB5070311 support notes.

Several independent reports from Windows news sites and testers confirm the same behavior and describe it as especially jarring in low-light conditions, since dark mode users suddenly get a bright flash.

The Invisible Password Icon on the Lock Screen

The lock-screen problem is related but not identical.

According to Microsoft’s own documentation, the password sign-in icon can disappear from the lock screen after installing the August 2025 non-security preview update KB5064081 or any later update on Windows 11 24H2 and 25H2.

What users see:

• On the lock screen Sign-in options, the password icon isn’t visible.
• The underlying button still works – if you hover or click roughly where it used to be, the password field appears and you can log in as normal.

Microsoft stresses that this is a UI bug, not a security issue: the password mechanism itself still functions.

One important detail from Microsoft’s explanation:
If password is your only sign-in method, Windows normally shows the password box directly and you won’t see this icon-vanishing behavior. The problem mainly affects systems that also have PIN, fingerprint, or Windows Hello as sign-in options. Microsoft Support

Who Is Affected?

Based on Microsoft’s notes and multiple independent reports, the issues affect:

• Windows 11 24H2 and 25H2 systems that:
  • have installed the optional preview KB5070311 (for the File Explorer white-flash bug)
  • have installed KB5064081 (August 2025 preview) or newer updates (for the invisible password icon)

If you haven’t installed optional preview updates and are only on standard cumulative “Patch Tuesday” releases, you’re less likely to run into these problems right now, though Microsoft’s own wording suggests the password icon bug can appear in “later updates” derived from KB5064081. Microsoft Support

Are There Any Workarounds?

Microsoft has not yet shipped a permanent fix for either issue. Officially, the company says it is investigating and will provide more information when a resolution is available.

Based on current documentation and reports, these are the realistic options:

For the File Explorer white-flash bug (KB5070311)

• Avoid or remove the update
  • If you haven’t installed KB5070311 yet, you can simply skip this optional preview until a patched version is available. Windows Latest
  • If you already installed it and the flashes bother you, you can uninstall KB5070311 from Settings → Windows Update → Update history → Uninstall updates (standard Windows behavior; multiple outlets recommend rolling back if affected).
• Switch File Explorer to light mode
  Microsoft doesn’t list this as an official workaround, but several reports note that the flashing only occurs in dark mode; using light mode side-steps the bug for now.

For the invisible password icon (KB5064081 and later)

• Click the “empty” space
  The password button is still present but invisible. Hover your mouse around where the password icon used to be in the lock-screen sign-in options and click – this should reveal the password field.
• Use your PIN or Windows Hello if available
  If you normally use Windows Hello (face/fingerprint) or a PIN, you can sign in that way and avoid the missing icon entirely, which Microsoft also suggests as behavior for affected systems.

At the time of writing, some outlets expect Microsoft may try to roll fixes into the December 2025 Patch Tuesday update, but Microsoft has not publicly guaranteed a date, so that remains an informed expectation, not a confirmed schedule.

Other Side Effects of KB5070311

While the original piece focused on the visual bugs, KB5070311 has been linked to a few additional issues in testing:

• Install failures with errors like 0x80070306
• Crashes and display issues on some systems with Intel Arc GPUs (reports of blue screens or black screens with a cursor after the update plus newer Arc drivers)

These aren’t universal, but they’re another reason some experts recommend avoiding this optional preview unless you specifically need its new features.

Updated Bottom Line

click the invisible button or use other sign-in methods when the password icon vanishes.

The File Explorer dark-mode white flash is a known bug tied to the Windows 11 KB5070311 preview update.

The invisible password sign-in icon on the lock screen stems from the KB5064081 August 2025 preview and later updates, and still exists on systems with KB5070311.

Microsoft has acknowledged both issues and is working on fixes, but there’s no confirmed patch date yet.

For now, the practical choices are:

skip or uninstall KB5070311 if you’re affected,

use light mode to avoid the File Explorer flash, and

Conclusion

For now, these Windows 11 glitches are more annoying than dangerous. The File Explorer white flashes and the missing lock screen password icon don’t affect your actual data or your ability to sign in, but they can make your PC feel less polished and more confusing – especially if you rely on dark mode or switch sign-in options often.

Because the problem stems from optional preview updates, the safest move for most people is simple: avoid installing them unless you specifically need a feature they provide. If you’ve already updated and are seeing these issues, your realistic choices are to uninstall the affected updates, switch File Explorer out of dark mode, or live with the bugs until Microsoft ships a fix.

As with any preview release, this is a reminder that “optional” updates really are optional. If stability matters more to you than testing the latest tweaks, it’s usually best to wait for the fully tested cumulative updates and let others discover the rough edges first.