17 Ways to Fix Assassin’s Creed Valhalla Not Launching on Windows 11 25H2

Windows 11 25H2 is not currently documented by Microsoft as causing a general Assassin’s Creed Valhalla launch failure. Microsoft previously documented a real compatibility problem affecting some Ubisoft games—including Valhalla—under Windows 11 24H2, but that history does not prove that every 25H2 failure has the same cause. Check the current Windows 11 25H2 release-health page before assuming the operating system is solely responsible.

For an official Ubisoft Connect, Steam, or Epic Games Store installation, work through the fixes below in order. The first steps target the most common and lowest-risk causes: a hung launcher, account handoff, outdated Windows or graphics drivers, corrupted files, overlays, missing runtimes, security software, and a damaged configuration. Do not download replacement DLLs, modified executables, cracks, or unofficial 25H2 patches.

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Identify what not launching means

The symptom determines which branch is most useful. A game that never creates a process points toward the launcher, account, security software, or missing files. A game that reaches the splash screen and closes is more often associated with configuration, drivers, runtimes, overlays, or graphics initialization. A black screen usually needs a display-mode, GPU-selection, driver, or overlay investigation.

Before you start

• Confirm whether your copy is installed through Ubisoft Connect, Steam, or Epic Games Store.
• Press Win + R, enter winver, and record the Windows version and OS build.
• Note the date Valhalla last worked and the date Windows 11 25H2 was installed.
• Temporarily remove mods, ReShade, trainers, injectors, overclocking profiles, and hardware-monitoring overlays.
• Back up %USERPROFILE%DocumentsAssassin's Creed Valhalla before resetting configuration or changing files. Depending on the edition and cloud-save state, this folder may contain saves as well as settings.

Check the current requirements

Meeting the minimum requirements does not guarantee that the game will launch after a Windows upgrade, but unsupported hardware creates a separate problem from 25H2 compatibility. Ubisoft’s original PC specification listed Windows 10 64-bit, DirectX 12, 8 GB of RAM, a Radeon R9 380 or GeForce GTX 960-class minimum GPU, and 50 GB of storage at launch. See the original Ubisoft PC specifications.

The current Steam listing still identifies Windows 10 64-bit, 8 GB of RAM, and DirectX 12, but currently displays 160 GB of available storage. Use the storefront associated with your edition as the current storage authority; do not repeat the original 50 GB figure as though it were necessarily the present installation requirement. Also verify that the graphics adapter supports DirectX 12 feature level 12_0, as specified in Ubisoft’s original requirements.

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Fix 1: Restart Windows and terminate hung launcher processes

Targets: A game that remains in Task Manager, a launcher that says the game is already running, or a launch attempt that silently returns to the library.

1. Press Ctrl + Shift + Esc to open Task Manager.
2. In Processes or Details, end any stuck ACValhalla.exe, Ubisoft Connect, Ubisoft Game Launcher, or upc.exe processes.
3. End Steam or Epic Games Launcher only if its handoff is also frozen.
4. Restart Windows rather than merely signing out.
5. Open the correct launcher, sign in, and start Valhalla normally.

Process names can change with Ubisoft Connect versions. End a process because it is clearly hung, not because it merely exists. Do not delete files from the game directory at this stage.

Expected result: Ubisoft Connect should show a fresh launch attempt and Valhalla should create a new process. If the process never appears, continue to Fix 2 and Fix 6.

Fix 2: Launch from the correct account and storefront

Targets: Ownership errors, login loops, Ubisoft Connect opening without starting the game, or Steam/Epic returning to the library.

1. Sign in to the Steam or Epic account that purchased or legitimately owns Valhalla.
2. Confirm that this account is linked to the Ubisoft account that owns or activated the game.
3. Open Ubisoft Connect manually and sign in before launching.
4. Start the game from Steam, Epic, or Ubisoft Connect—not by bypassing the launcher with a desktop executable.

PC access can require a Ubisoft account and Ubisoft Connect under Ubisoft’s end-user license terms. Steam’s technical-support page for Valhalla also routes many game-specific issues to Ubisoft. If Ubisoft Connect says the game is not owned, resolve account linking, activation, or login issues first. Reinstalling Windows, replacing executables, or downloading a different launcher will not fix an account entitlement problem.

Expected result: Ubisoft Connect should show Valhalla in the correct library and accept the launch handoff. If ownership is correct but the handoff fails, proceed to file verification.

Fix 3: Install current Windows 11 25H2 updates

Targets: A failure that started after an incomplete upgrade, an outdated Windows component, or a recently fixed driver and servicing issue.

1. Open Settings > Windows Update.
2. Select Check for updates.
3. Install available cumulative updates. Review optional driver updates and install them when they are appropriate for your hardware.
4. Restart Windows even if the update process does not explicitly require it.
5. Run winver again and record the resulting version and OS build.

Windows 11 25H2 has had issues requiring cumulative or out-of-band updates. For example, Microsoft documented a Dell/Intel driver issue resolved through KB5121767 on July 18, 2026. That issue was not specific to Valhalla, but it demonstrates why a fixed KB number should not be treated as a universal gaming fix. Check the live 25H2 release-health page and the Windows 11 25H2 update history instead.

Recovery: If Windows Update reports an error, resolve the Windows servicing problem first. Do not uninstall the latest update simply because Valhalla fails; rollback is a late diagnostic step described below.

Fix 4: Update or clean-install the graphics driver

Targets: A splash-screen crash, black screen, failure after a Windows upgrade, or a game that launches only on one monitor or GPU.

1. Download a current stable driver before removing or replacing the existing one.
2. Use the official page for your GPU: NVIDIA, AMD, or Intel.
3. For a laptop, check the laptop manufacturer’s support page too; OEM drivers may contain power-management or display customizations.
4. Choose the vendor’s clean-install option when available.
5. Restart Windows and test Valhalla before re-enabling overlays, overclocks, or monitoring utilities.

Do not hard-code a driver version into a troubleshooting guide: the current stable release changes. If the newest driver is already installed and the failure began immediately after that driver, test the laptop or GPU manufacturer’s prior stable branch rather than randomly installing files from an unofficial site.

For an optional second opinion on the Windows hardware-driver state, Outbyte Driver Updater can help identify missing or outdated drivers, but use the GPU or laptop manufacturer’s official package for the final installation.

Expected result: The game should initialize the graphics device and show a window. If it still launches on the wrong adapter, use Fix 5.

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Fix 5: Assign Valhalla to the high-performance GPU

Targets: Laptops and hybrid-graphics systems where Valhalla starts on integrated graphics, producing a black screen or an immediate close.

1. Open Settings > System > Display > Graphics.
2. Under desktop-app graphics options, select Browse.
3. Browse to ACValhalla.exe in the game’s installation folder and add it.
4. Select Valhalla in the list.
5. Choose Options > High performance > Save.
6. Restart the game through its normal launcher.

If you cannot find the executable, use the launcher’s Browse local files command or inspect the installation directory shown by Steam, Epic, or Ubisoft Connect. Do not select an unrelated executable merely because its name contains Ubisoft.

Windows’ per-application graphics assignment is preferable to changing BIOS settings while diagnosing. If the high-performance option is unavailable, update the GPU driver and check whether Windows detects both adapters correctly in Device Manager.

Fix 6: Verify the game files

Targets: Missing or damaged files, a failed patch, an antivirus quarantine event, or a game that closes before displaying an error.

Ubisoft Connect

1. Open Ubisoft Connect and select Games.
2. Open the Valhalla game page.
3. Open the game’s options menu.
4. Choose Verify files and allow the scan and reacquisition process to finish.

Ubisoft documents this procedure in its Ubisoft Connect PC file-verification guide.

Steam

1. Open Library and right-click Valhalla.
2. Choose Properties > Installed Files.
3. Select Verify integrity of game files.

Steam’s current instructions are in its file-verification FAQ.

Epic Games Store

1. Open the Epic Games Library.
2. Select the three-dot menu next to Valhalla.
3. Choose Manage > Verify.

Expected result: Missing or corrupted files are downloaded again. If antivirus immediately quarantines the same legitimate file, verification alone will not solve the problem; continue with Fix 12 and inspect Protection history.

Fix 7: Disable Ubisoft Connect and third-party overlays

Targets: A splash-screen crash, black screen, failure after a launcher update, or a game that works in a clean boot but not during normal startup.

1. Open Ubisoft Connect.
2. Open Settings and find the in-game overlay option.
3. Turn the Ubisoft Connect overlay off.
4. Restart Ubisoft Connect and test Valhalla.

Ubisoft provides instructions for disabling the Ubisoft Connect PC overlay. Also temporarily disable Steam Overlay, Epic overlay, Discord overlay, Xbox Game Bar, NVIDIA App or GeForce overlay, AMD Adrenalin overlay, MSI Afterburner/RivaTuner OSD, ReShade, RGB utilities, audio-enhancement software, and hardware-monitoring tools.

Disable one category at a time if possible. When Valhalla launches, re-enable the tools individually until the conflict returns. That identifies the culprit without permanently sacrificing the features you use.

Fix 8: Reset the Ubisoft Connect cache

Targets: A stale launcher session, incorrect library state, repeated login behavior, or a game that is visible but will not hand off from Ubisoft Connect.

This is a common community troubleshooting procedure. Ubisoft’s current public help results do not expose a consistently indexed, version-specific official cache-reset article, so treat it as community-derived rather than a guaranteed Ubisoft fix.

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1. Exit Ubisoft Connect.
2. Right-click the Ubisoft Connect icon in the notification area and choose Exit.
3. Open Task Manager and confirm that no Ubisoft processes remain.
4. Open the Ubisoft Game Launcher installation folder, commonly C:Program Files (x86)UbisoftUbisoft Game Launcher.
5. Rename the folder named cache to cache.old.
6. Start Ubisoft Connect, sign in, and test Valhalla.

Folder names and installation paths can change. If your launcher is elsewhere, open the Ubisoft Connect shortcut’s Properties and inspect its target location. Rename rather than permanently delete the cache so it can be restored if necessary. Do not delete the game installation folder or the Documents save folder.

Fix 9: Repair both Visual C++ Redistributable architectures

Targets: Errors naming a missing Visual C++ runtime or DLL, and some silent startup failures caused by damaged runtime components.

Install or repair both supported Microsoft packages:

• Visual C++ Redistributable x64
• Visual C++ Redistributable x86

1. Run the x64 installer and choose Repair if it is already installed, or Install if it is missing.
2. Repeat with the x86 installer.
3. Restart Windows.
4. Test Valhalla from the correct launcher.

A 64-bit game can still depend on 32-bit auxiliary components, launchers, installers, or tools. Microsoft explains the supported packages in its Visual C++ Redistributable documentation. Repairing Visual C++ is most relevant when the error identifies a runtime component; it is not a guaranteed cure for every silent crash.

Never download an individual MSVCP, VCRUNTIME, or other DLL from a random DLL website. Use the official Microsoft installers or the game’s verified files.

Fix 10: Install the legacy DirectX side-by-side runtime only when the error requires it

Targets: Messages mentioning D3DX, XAudio2_7, XInput1_3, XACT, or another older DirectX component.

Windows 11 already includes the operating-system DirectX runtime. Microsoft’s DirectX End-User Runtime Web Installer adds older side-by-side libraries used by some applications; it does not upgrade or replace DirectX 12.

1. Verify Valhalla’s files first with Fix 6.
2. Repair Visual C++ with Fix 9 if appropriate.
3. Use Microsoft’s DirectX End-User Runtime only if the error identifies a legacy component or the game installer specifically requires it.
4. Restart Windows and test again.

Do not present DirectX June 2010 as a universal Windows 11 25H2 launch fix. A DirectX 12 feature-level problem, a GPU driver problem, and a missing legacy D3DX library are different failure classes.

Fix 11: Install the Media Feature Pack on Windows 11 N

Targets: Windows 11 N editions, which omit certain media technologies that games and related services may use.

1. Open Settings > Apps > Optional features.
2. Select View features beside Add an optional feature.
3. Search for Media Feature Pack.
4. Install it and restart Windows.

Microsoft describes the package in its Media Feature Pack list for Windows N editions. This is an N-edition-only remedy. It is not necessary on standard Windows 11 Home, Pro, or Enterprise installations.

Fix 12: Check Windows Security and Controlled Folder Access

Targets: Nothing happens, a file disappears after verification, or Valhalla and Ubisoft Connect cannot save configuration data.

1. Open Windows Security.
2. Go to Virus & threat protection.
3. Select Manage ransomware protection.
4. Choose Allow an app through Controlled folder access.
5. Add the genuine Valhalla executable and Ubisoft Connect executable if Windows Security shows that they were blocked.
6. Open Protection history and inspect quarantined items.
7. Restore a file only when you have confirmed that it is the genuine file from the official installation.
8. Verify the game files again after resolving the detection.

Microsoft’s Controlled Folder Access guidance explains how to allow a legitimate application. Prefer an allow-list entry and a vendor quarantine review over permanently disabling protection.

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A brief, offline diagnostic test with real-time protection disabled can sometimes confirm a security conflict, but it should not be the default fix. Restore protection immediately, do not browse or download files while it is disabled, and never bypass a repeated detection by downloading a replacement executable. If the same legitimate file is repeatedly quarantined, submit it to the antivirus vendor for analysis.

Fix 13: Perform a clean boot

Targets: Conflicts with an overlay, RGB controller, audio utility, security product, monitoring application, VPN, or other third-party service.

1. Press Win + R, enter msconfig, and press Enter.
2. Open the Services tab.
3. Check Hide all Microsoft services.
4. Select Disable all.
5. Open the Startup tab and select Open Task Manager.
6. Disable nonessential startup items.
7. Restart Windows and test Valhalla.

Use Microsoft’s official clean-boot procedure if the labels differ. If the game works, the clean boot has identified a third-party conflict—not necessarily a 25H2 defect. Restore Normal startup in System Configuration and re-enable services in batches. Do not leave security, networking, audio, or hardware services disabled indefinitely.

Fix 14: Reset Valhalla’s local configuration safely

Targets: The splash screen appears and closes, the game remains as a background process, or a black screen began after a graphics, monitor, HDR, or display-mode change.

1. Close Valhalla and Ubisoft Connect.
2. Make a complete backup of %USERPROFILE%DocumentsAssassin's Creed Valhalla to another folder or drive.
3. Rename the original folder to Assassin's Creed Valhalla.old.
4. Start Valhalla through the normal launcher.
5. If it launches, close it and restore saves or individual settings carefully from the backup.

Community reports commonly identify the Documents folder and ACValhalla.ini as configuration locations, but Ubisoft’s current public support pages do not provide a definitive, version-specific configuration-reset procedure. Renaming the folder is therefore a reversible, community-derived test—not an official guaranteed fix.

Save warning: Do not simply delete this folder. It may contain local saves or other user data depending on your edition and cloud-save state. Confirm that Ubisoft cloud synchronization is enabled if you rely on it, and do not overwrite a newer local save with an older cloud copy.

Fix 15: Test fullscreen optimizations and windowed mode

Targets: Black screen, a window that opens outside the visible desktop, or a game that closes during display initialization.

1. Use the launcher’s local-files option to locate ACValhalla.exe.
2. Right-click it, choose Properties, and open Compatibility.
3. Check Disable fullscreen optimizations, select Apply, and test the game through the normal launcher.
4. If the game has generated an INI configuration file, use your backup to test windowed mode only when you can restore the original setting.

Community reports have suggested changing a WindowMode value, but the setting is version-sensitive and unofficial. Do not edit a configuration file without a backup, and do not assume that Windows 7 or Windows 8 compatibility mode is helpful. Compatibility mode can introduce new launcher or graphics problems, so treat it as a late diagnostic experiment rather than a standard fix.

Fix 16: Repair Windows system files with DISM and SFC

Targets: Broader Windows corruption, failed servicing, or multiple applications showing unexplained startup failures.

1. Open Command Prompt as administrator.
2. Run:

DISM.exe /Online /Cleanup-Image /RestoreHealth

Allow DISM to finish. Then run:

sfc /scannow

Restart Windows and test Valhalla again. Microsoft recommends running DISM before System File Checker; see its DISM and SFC guidance.

If SFC reports that it found no integrity violations, that means protected Windows files were not corrupt; it does not prove that Valhalla has no problem. If DISM fails, resolve the Windows servicing error before repeatedly reinstalling the game.

If DISM or SFC points to broader Windows corruption, Outbyte PC Repair is an optional way to review related repair issues alongside Microsoft’s commands, not a substitute for them.

Fix 17: Clean-reinstall Ubisoft Connect, then Valhalla if necessary

Targets: A damaged launcher installation, broken launcher-to-game handoff, or a game that still fails after files, runtimes, drivers, security, and configuration have been checked.

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1. Back up the Documents folder and note Valhalla’s installation location.
2. Uninstall Ubisoft Connect from Settings > Apps > Installed apps.
3. Restart Windows.
4. Download the current installer from Ubisoft’s official Ubisoft Connect download page.
5. Install it and sign in to the correct Ubisoft account.
6. Allow Ubisoft Connect to rediscover the existing game installation if that option is available, or reinstall Valhalla.
7. Verify the game files again.
8. Test the unmodified game before reinstalling overlays, mods, or monitoring tools.

Uninstalling the launcher does not make a backup unnecessary. Record the game’s location and preserve saves before proceeding. Reinstalling the whole game is expensive and should follow, not precede, file verification and launcher repair.

Keeping Ubisoft Connect and Valhalla on the same local NTFS drive is sometimes reported as helpful, but it is not established by Ubisoft’s cited documentation as a universal requirement. If you use this as an optional diagnostic, avoid network, removable, or cloud-synchronized game folders; leave ample free space; and do not install the game inside C:Windows or another protected operating-system directory.

If none of the 17 fixes works

At this point, stop applying random tweaks and narrow the fault. Test whether:

• A second Ubisoft game launches. If several Ubisoft games fail, prioritize Ubisoft Connect, Windows updates, the GPU driver, and security software.
• Valhalla launches under a new local Windows user profile. This can distinguish a damaged user profile from a system-wide problem.
• A clean boot changes the result. If it does, re-enable services and startup items in batches.
• A newly created Valhalla configuration folder changes the result. Preserve the original backup and saves.
• Returning GPU, CPU, RAM, motherboard, and undervolt settings to stock changes the result. One game can expose an instability that other workloads do not.

Collect evidence before contacting support:

• Reliability Monitor: press Win + R and run perfmon /rel.
• Event Viewer: run eventvwr.msc, then inspect Windows Logs > Application at the launch time.
• DirectX Diagnostic Tool: run dxdiag and save the report.
• System Information: run msinfo32 and save the report.

When contacting Ubisoft Support, include your Ubisoft account and storefront, Windows version and OS build from winver, GPU model and driver version, the exact symptom, any error text, whether file verification completed, whether overlays were disabled, whether security software blocked anything, and the relevant crash or diagnostic files.

Should you roll back Windows 11 25H2?

Rollback should not be the default solution. It can remove security updates, may be unavailable after the rollback window, and is not justified merely because Valhalla fails after an upgrade. First test the launcher, account, current cumulative updates, GPU driver, game files, overlays, runtimes, security controls, and configuration.

Consider rollback only as a documented diagnostic when the failure began immediately after a clearly identified Windows update, affects more than one Ubisoft game, and remains reproducible after the other causes have been ruled out. Record the winver result, Windows Update history, GPU and driver version, storefront, exact symptom, Reliability Monitor or Event Viewer fault, and clean-boot result. Check Microsoft’s release-health information and contact Ubisoft or Microsoft rather than using an unofficial downgrade package or a so-called 25H2 crack fix.

Why the 25H2 diagnosis matters

The historical Windows 11 24H2 issue was real: Microsoft described some Ubisoft games becoming unresponsive while starting, loading, or playing, sometimes with a black screen, and applied a compatibility hold to affected devices. That is useful context for someone whose problem began during a Windows upgrade. However, Microsoft’s current Windows 11 25H2 release-health page does not identify a general Assassin’s Creed Valhalla or Ubisoft-game launch defect.

The practical conclusion is not that 25H2 can never be involved. A particular GPU driver, launcher build, security rule, configuration, or hardware combination can still fail after an operating-system update. It means there is no verified universal 25H2 fix to apply to every PC. Diagnose the specific failure instead.

Frequently Asked Questions

Will verifying Valhalla’s files delete my saves?

File verification normally reacquires missing or damaged installation files, not the Documents save folder. Even so, back up %USERPROFILE%DocumentsAssassin's Creed Valhalla before any configuration reset or reinstall, and check cloud-save status before restoring files.

Should I install DirectX June 2010 on Windows 11 25H2?

Only when an error names a legacy component such as D3DX, XAudio2_7, or XInput1_3, or an installer specifically requires it. Microsoft’s legacy DirectX package adds side-by-side libraries; it does not upgrade DirectX 12.

Is Windows 11 25H2 officially incompatible with Assassin’s Creed Valhalla?

Microsoft does not currently list a general Valhalla launch defect for 25H2. Microsoft did document a related issue affecting some Ubisoft games under 24H2, so a particular PC can still have an update-related conflict without every 25H2 installation being broken.

Can I download a replacement ACValhalla.exe or DLL if antivirus removed it?

No. Check Windows Security Protection history or your antivirus quarantine, restore the file only after confirming it is genuine, and then verify the game through Ubisoft Connect, Steam, or Epic. Do not use file-sharing sites, cracks, or modified executables.

When should I contact Ubisoft Support?

Contact support after collecting the Windows build, GPU and driver details, storefront, exact symptom, verification result, security or overlay findings, and relevant Reliability Monitor, Event Viewer, dxdiag, or msinfo32 information. Several Ubisoft games failing together is especially useful evidence.

The Bottom Line

Start with the launcher and files, not a Windows rollback. Restart stuck processes, confirm the correct account, update Windows and the GPU driver, verify Valhalla, disable overlays, and then investigate runtimes, security software, configuration, and background conflicts. Windows 11 25H2 may expose a particular compatibility problem, but there is no currently verified universal Valhalla launch defect or single official 25H2 fix.

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