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One free scan finds every outdated or missing driver and matches the right update for your exact hardware.Free scan · exact hardware matchcallbuttons.proxystub.dll is a legitimate Microsoft Windows component, so do not replace it with a random DLL download. The safest fix for a missing, corrupt, or unloadable copy is to update Windows and repair its component store with DISM followed by System File Checker.
What this file actually does
The file’s documented description is “Windows Runtime CallButtonsServer ProxyStub DLL.” It belongs to Windows rather than to a Visual C++ Redistributable, DirectX, .NET, printer driver, or ordinary game library.
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The ProxyStub part of the name refers to a COM and Windows Runtime support component. Proxy/stub DLLs help software communicate with objects across process boundaries by converting method calls and data into a form another process can use. This file is associated with Windows call-control and media-device infrastructure, including the Windows.Media.Devices.Internal.CallControlBroker component.
Public Windows binary inventories associate it with Windows 8, Windows 8.1, Windows 10, Windows 11, and corresponding Windows Server releases. The exact file version depends on the installed Windows build. Windows DLL inventory
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On 64-bit Windows, the normal locations are:
%windir%System32CallButtons.ProxyStub.dll
%windir%SysWOW64CallButtons.ProxyStub.dll
Despite its name, System32 contains native 64-bit system files on 64-bit Windows. SysWOW64 contains the 32-bit system files used by 32-bit applications. This naming is documented by Microsoft’s file-system redirector documentation.
A program may display the error even when the named DLL exists. “The specified module could not be found” can mean that a dependency required by the DLL is missing, not necessarily that CallButtons.ProxyStub.dll itself is absent.
Error symptoms and likely causes
| What you see | Most likely explanation | Start here |
|---|---|---|
| “The program can’t start because CallButtons.ProxyStub.dll is missing from your computer” | The file is missing or Windows cannot access it | Windows Update, DISM, then SFC |
| “CallButtons.ProxyStub.dll was not found” | The loader cannot find the expected system component | Check the correct system directory and repair Windows |
| “Error loading CallButtons.ProxyStub.dll. The specified module could not be found” | The DLL or one of its dependencies cannot load | DISM/SFC, then inspect the affected application |
| “CallButtons.ProxyStub.dll is either not designed to run on Windows or it contains an error” | Wrong architecture, mismatched build, corruption, or a damaged dependency | Repair Windows rather than copying another DLL |
| The problem started after antivirus detection | The file may have been quarantined, or the detection may involve a suspicious copy | Check Protection History before restoring anything |
| Only one application fails | The application may have damaged files or an incompatible integration | Repair or reinstall that application |
These messages are generic Windows loader errors. The “not designed to run on Windows” wording, sometimes accompanied by status 0xc000012f, does not by itself prove that this DLL is the root cause.
Fix 1: Restart and install pending Windows updates
A failed or incomplete Windows servicing operation can leave protected system files unavailable. Start with the least invasive repair.
- Restart the computer.
- Open Start > Settings > Windows Update.
- Select Check for updates.
- Install all available updates.
- Restart when Windows requests it.
- Open the application or Windows feature that produced the error.
If the error returns, continue with DISM and SFC. Do not download a replacement DLL first.
Fix 2: Repair Windows with DISM and SFC
Microsoft recommends repairing the Windows image before running System File Checker. DISM repairs the component store, which provides the source files SFC uses to restore protected files.
- Open Start.
- Type Command Prompt.
- Right-click Command Prompt and select Run as administrator.
- Approve the User Account Control prompt.
- Run this command:
cmd
DISM.exe /Online /Cleanup-Image /RestoreHealth
Do these 3 things before closing this tab:
1Repair Windows errors before they cause bigger problems2Fix the driver behind crashes, sound loss and screen glitches3Clear out junk files and repair common Windows errors- Wait for DISM to finish. Do not close the window if progress appears to pause.
- After DISM completes successfully, run:
cmd
sfc /scannow
- Wait until verification reaches 100 percent.
- Restart Windows and test the affected program.
SFC may report that it repaired corrupted files, found no integrity violations, or found corruption it could not repair. The first two outcomes are useful: restart and test again.
Outbyte PC Repair can reduce the guesswork when you are repeatedly hunting through Windows repairs and cannot tell what changed; its free scan shows detected issues, while repair is performed by the full version. It is optional, and Windows servicing remains the correct first-line repair for this Microsoft component.
If DISM or SFC cannot repair the file
If SFC says that it found corrupt files but could not fix some of them, run DISM again, restart, and repeat SFC. Then inspect the servicing log:
%windir%LogsCBSCBS.log
If DISM says that source files could not be found, an alternate source may be needed:
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C:RepairSourceWindows is only a placeholder. The repair source must match the installed Windows edition and build. Do not use an arbitrary folder or an unrelated Windows installation. Microsoft provides additional component-store repair guidance.
Fix 3: Check antivirus quarantine
If the error appeared immediately after Microsoft Defender or another antivirus product detected a file, check whether a copy was quarantined.
For Microsoft Defender:
- Open Start > Settings.
- Select Privacy & security > Windows Security.
- Open Virus & threat protection.
- Select Protection history.
- Review recent detections involving the DLL or its directory.
Do not automatically restore the file. Restore a quarantined file only after confirming that it was the genuine Microsoft-supplied copy, was originally located in a Windows system directory, and is digitally signed by Microsoft. Microsoft notes that restoring a quarantined file makes it active again. See its Protection History guidance.
If the detection concerns a copy in a game directory, temporary folder, download directory, or user profile, leave it quarantined and run a full security scan. A same-named DLL outside %windir% deserves closer investigation.
Fix 4: Repair the application that reports the error
Although the DLL is a Windows component, one application may be the only program that calls the affected Windows feature. If Windows Update, DISM, and SFC complete successfully but one program still fails, repair that program.
For a packaged application:
- Open Start > Settings > Apps > Installed apps.
- Find the affected application.
- Select its three-dot menu.
- Choose Advanced options.
- Select Repair.
- Test the application.
For classic desktop software:
- Open Control Panel.
- Select Programs > Programs and Features.
- Right-click the affected program.
- Choose Repair or Change.
- Follow the installer’s instructions.
If repair does not help, uninstall the application, restart Windows, and reinstall it using the developer’s official installer. Use the application’s own update or file-verification feature where available. Reinstalling the application is the definitive fix when its private files or installation registration are damaged, but it should not replace Windows repair when the system component itself is missing.
Microsoft documents these steps in its guide to repairing apps and programs.
Fix 5: Check architecture and the expected path
A 32-bit process normally uses the 32-bit Windows component under SysWOW64; a 64-bit process uses the native component under System32 on 64-bit Windows. The file name alone does not tell you which copy an application needs.
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To identify an application’s architecture, check its documentation or installation directory, or ask its developer. In Task Manager, some 32-bit processes are marked with “(32 bit)” on supported Windows versions. A 32-bit application commonly runs from locations such as C:Program Files (x86), although the folder location is not conclusive.
Do not copy the same file into both directories. Windows servicing must restore the correct architecture and build. A file taken from another Windows release can cause the “not designed to run on Windows” message or create a dependency mismatch.
Fix 6: Do not start with drivers unless the evidence points there
This DLL is not established as a driver-package file. Update drivers only if the same failure began with a separate audio, Bluetooth, headset, camera, or media-device problem, or if Device Manager reports a device error.
To check Device Manager:
- Right-click Start.
- Select Device Manager.
- Expand relevant categories such as Sound, video and game controllers or Bluetooth.
- Right-click the affected device.
- Select Update driver.
- Choose Search automatically for drivers.
- Restart Windows if a driver is installed.
Outbyte Driver Updater can show which drivers it detects as stale instead of making you inspect many devices manually; its free scan identifies issues, while driver installation is handled by the full version. It is optional, and a driver update is not a substitute for restoring this Windows DLL through servicing.
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Fix the driver behind crashes, sound loss and screen glitchesFind Drivers →Repair Windows errors before they cause bigger problemsFix Now →Fix 7: Use System Restore or repair-reinstall Windows
If the problem began after a recent system change and DISM/SFC cannot repair it, System Restore may return Windows to an earlier working state.
- Open Start and search for Create a restore point.
- Open the result.
- Select System Restore.
- Choose a restore point dated before the error began.
- Review the affected programs and confirm the restore.
- Restart and test Windows.
System Restore does not replace a personal backup. Save important work before recovery operations. Microsoft lists this and other options in its Windows recovery guide.
On Windows 11, you may also see Fix problems using Windows Update > Reinstall now under Settings > System > Recovery. When available, this reinstalls the current Windows version while preserving apps, files, and settings. Follow the on-screen instructions and back up important data first.
If those options are unavailable or repeatedly fail, an in-place Windows repair using installation media matching the installed edition and architecture is the next advanced step. If the computer has disk errors, malware concerns, or repeated component-store failures, address those issues before attempting further repairs.
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Why downloading the DLL is a bad fix
Random DLL download sites can provide malware, the wrong Windows build, the wrong architecture, or a file with an invalid signature. Even a genuine-looking file may not match the component store or its dependent files, so copying it into System32, SysWOW64, or an application folder can leave Windows in an inconsistent state.
There is no separate Microsoft redistributable that is known to supply CallButtons.ProxyStub.dll, and Microsoft does not publish a standalone download page for this particular component. Use Windows Update, DISM, SFC, recovery tools, or a trusted Windows installation source instead.
regsvr32 is not a general missing-DLL repair command. It is intended for DLLs that provide the required registration entry points. Although some COM proxy DLLs can be registerable, there is no authoritative basis for treating manual registration of this Windows component as a routine fix. Do not run:
regsvr32 CallButtons.ProxyStub.dll
unless Microsoft or the component’s documented support procedure specifically requires it.
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Verify a suspicious copy
If the file exists, check both its location and signature.
- Open File Explorer.
- Browse to
%windir%System32or%windir%SysWOW64. - Right-click
CallButtons.ProxyStub.dll. - Select Properties.
- Open the Digital Signatures tab.
- Inspect the signer and select Details.
- Confirm that Windows reports a valid Microsoft signature.
A copy with the same name in a temporary directory, download folder, game directory, or user profile is not automatically legitimate. Do not delete a system file manually. Repair Windows and investigate suspicious copies with Windows Security.
FAQ
Is callbuttons.proxystub.dll a virus?
The legitimate file is a Microsoft Windows system DLL. A same-named file outside a Windows directory, or one without a valid Microsoft signature, requires investigation.
Should I put it in System32 or SysWOW64?
Do not manually copy it. On 64-bit Windows, native 64-bit files belong in System32 and 32-bit files in SysWOW64, but Windows servicing must select the correct build and architecture.
Is it part of Visual C++ or DirectX?
No. It is associated with Windows call-control and media-device infrastructure, not those redistributables.
Why does only one application show the error?
That application may be the only program using the affected Windows feature, or its own installation may be damaged. Complete DISM and SFC first, then repair or reinstall the application.
What should I do if nothing works?
Review %windir%LogsCBSCBS.log, check disk health, inspect antivirus history, try System Restore, and consider a Windows repair reinstall. Contact the application vendor when only its program fails after Windows reports no component corruption.
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