Anki opens to a blank window after Qt6WebEngineCore.dll errors on Windows

Anki Help
1

Hi everyone,

I’m using Anki on Windows 11. After launching Anki, I first got this error:

“QtWebEngineProcess.exe - System Error: The code execution cannot proceed because Qt6WebEngineCore.dll was not found.”

I tried reinstalling Anki, but the problem continued. I also found that Qt6WebEngineCore.dll existed in:

C:\Users\DELL\AppData\Local\Programs\Anki\lib\PyQt6\Qt6\bin\Qt6WebEngineCore.dll

After uninstalling/reinstalling and cleaning some folders, Anki now opens, but the window is completely blank/white. The menu bar appears, but the main interface does not load.

Things I have tried:

  • Reinstalling Anki

  • Running anki-console.exe

  • Deleting/cleaning AnkiProgramFiles

  • Checking Windows Defender protection history

  • Checking for Qt6WebEngineCore.dll

  • Restarting Windows

My current issue:
Anki starts, but the main window is blank white.

Could someone please tell me the correct way to fully clean the broken Qt/Anki installation and reinstall Anki safely? I want to avoid this

anki 1
anki 11917×1077 21 KB

.

Thank you.

2

Please try Troubleshooting Step #6, changing the video driver. (Remember to quit and restart Anki each time after you make a change to the video driver settings.)

3

Anki used to work perfectly, now when I launch it i get this error and a blank window behind like this. I am on windows 11 25H2 with all updates installed as of 2nd june 2026. I saw this topic in the forum multiple times but there were no working fixes posted. Anki is on version 25.02.7. I earlier had 25.09 and when it had this same issue, i reverted to 25.02 but it still didnt work. I have tried clean reinstall to default location, disabling windows security and reboots, nothing works

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4

When you reverted, did you do that through Tools > Upgrade/Downgrade and the “Launcher” menu? If so, you’re still using the same launcher version, so if the problem came with the launcher, you haven’t escaped it.

When you did that, did you uninstall what you had first? Did you also delete these 2 program folders – Managing Files - Anki Manual – so the install would be completely clean?

After you do that, you can download 25.02.7 and directly install it – Release 25.02.7 · ankitects/anki · GitHub . Or you can try the latest beta build – Release 26.05b2 · ankitects/anki · GitHub (download the msi file under Assets). Both of those will avoid the launcher process.

5

I did a clean uninstall with those folders included and then installed the old version via the latest terminal installer you have on your website. I’ll try installing via directly downloading the old version from your link

6

removed all folders you mentioned, installed the beta version from the link you provided, still get this. Is there any way to generate logs for the devs to read?

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7
9

Didn’t work, tried via cmd and powershell just like the steps said

10

Did you try via the Preferences interface, or does that window not load for you?

Did you try all of the options, and did you restart after every change?

11

I cannot access the preferences menu or any menu, it does nothing when i click the options on top like File, Edit etc. I tried all the commands for windows in that article. Reopened and closed after each command. I tried both the powershell and the cmd, both running as administrator.

12

For now, you should probably go back to the pre-launcher version you were using before since you know that worked. First uninstall this version and delete both of those folders again, so you can start with a clean slate. I’d also recommend deleting the specific driver-mode file(s) you created in Anki2 – Display Issues - Anki Manual – and I mean just those files, not the entire folder.

13

That won’t work . I just opened it one day and it stopped working and threw this error, even before it updated to the launcher version which still crashed with the same error.

14

You’re free to reject my advice and try someting else, but I don’t think you can say for sure that it won’t work until you’ve tried it.

Given that additional information – it almost certainly has to do with something else happening on your system, outside of Anki. You might have other Qt apps (especially ones that were recently installed/updated) that have changed environment variables or registry keys, or are using a different version of Qt.

I’m not sure how to help you troubleshoot that, but maybe try –

  • Look in Task Manager for any qt processes and figure out where those are running from and what apps they belong to.
  • Search your computer for files/folders named qt. Can you find that DLL that Anki can’t find? Where is it?
16

Could reinstalling windows work?

Can I just download the missing dll?

17

I would never recommend reinstalling Windows. That seems like you’d lose far more than you’d gain.

We’re still not sure if that DLL is missing or in the wrong place, or if Anki just can’t find it. :person_shrugging:t4:

But if you’re getting this error, it means at least that file is missing, and there’s something not functioning correctly in your install, so I’m not sure obtaining a single file would cure this. That’s why I made the suggestions I did.

18

Actually windows has a new feature it can reinstall windows via windows update without losing any files or programs. It just installs the entire current version as an update like you’d do for a major update years ago ( before they added incremental updates).

19

Not my area of expertise, so that’s totally up to you.

20

I met the same problem,so i used claude code to help me to figure out the problem .I think this might be the true reason:

Anki’s main interface is rendered by QtWebEngineProcess.exe, a Chromium-based child process spawned by QWebEngineView. On startup, this child process attempts to create a GPU-accelerated OpenGL ES 3.0
graphics context for hardware rendering. On this system, the GPU driver fails to create that context, causing the child process to crash with a fatal error during initialization:

ERROR:gpu_channel_manager.cc(959)] Failed to create GLES3 context, fallback to GLES2.
ERROR:gpu_channel_manager.cc(970)] ContextResult::kFatalFailure:
Failed to create shared context for virtualization.

When the child process crashes, the main window receives no rendered content, resulting in a completely blank/white interface.

The earlier “Cannot find Qt6WebEngineCore.dll” error dialog was misleading — the DLL file (154MB, located at PyQt6\Qt6\bin\Qt6WebEngineCore.dll) was always present and intact. Windows simply reported the
wrong error when the child process failed to start.

Solution

Set the environment variable QTWEBENGINE_CHROMIUM_FLAGS to --no-sandbox --disable-gpu before launching Anki.

Temporary (per-session, PowerShell):

$env:QTWEBENGINE_CHROMIUM_FLAGS = “–no-sandbox --disable-gpu”

Permanent (user-level, survives reboots, PowerShell):

[Environment]::SetEnvironmentVariable(“QTWEBENGINE_CHROMIUM_FLAGS”,“–no-sandbox --disable-gpu”,“User”)

After setting permanently, restart Explorer (or log out and back in) for the change to take effect when double-clicking anki.exe.

--disable-gpu forces software rendering via CPU, bypassing the failing GPU hardware acceleration path. --no-sandbox disables Chromium’s sandbox isolation, which can also fail to initialize on some Windows
configurations when GPU initialization has already broken the process setup.

Anki’s own code (aqt/init.py) already applies --disable-gpu on Linux by default, but not on Windows, where GPU acceleration is assumed to work on all systems.

Environment

  • Anki version: 25.09.4, installed via uv with managed Python 3.13.5 at %LOCALAPPDATA%\AnkiProgramFiles\
  • Qt versions: Core 6.9.1, WebEngine 6.8.2 (the official combination pinned by anki-release==25.09.4)
  • OS: Windows 11
  • GPU: OpenGL ES 3.0 context creation fails with kFatalFailure
21

Wow, never knew claude code could do that type of serious troubleshooting. I’ll try it out before I refresh windows ig. Thanks for the idea

22

didn’t expect it either. but it really works on my laptop.