Start with this quick diagnosis
Before replacing anything, note:
- Which program shows the error: Windows itself, an application, an installer, or a game.
- When it appears: at startup, after an update, after antivirus cleanup, or only when opening one program.
- Which Windows architecture you use: open Settings → System → About and check System type.
- Where the file is located: the expected Windows locations are
%SystemRoot%System32SyncHostps.dlland, on 64-bit Windows,%SystemRoot%SysWOW64SyncHostps.dll.
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Outbyte PC Repair FREEClear out junk files and repair common Windows errorsFree Scan →Outbyte Driver Updater FREEFix the driver behind crashes, sound loss and screen glitchesFind Drivers →synchostps.dll is a genuine Microsoft Windows system file. Its description is “Proxystub for sync host”, so a missing or damaged copy should normally be repaired through Windows servicing rather than downloaded separately.
Fix 1: Repair Windows automatically with DISM and SFC
This is the safest first repair when Windows reports that synchostps.dll is missing, corrupted, could not be loaded, or is not designed to run on Windows. Microsoft recommends running DISM before System File Checker because SFC can use the repaired component store to restore protected files.
1. Install pending updates
- Open Start → Settings.
- Select Windows Update.
- Click Check for updates.
- Install available updates and restart when asked.
If the error began immediately after a failed update, restarting and completing pending servicing can restore the file without further work.
2. Run DISM as administrator
- Open Start.
- Type Command Prompt.
- Right-click Command Prompt and select Run as administrator.
- Choose Yes if User Account Control appears.
- Enter:
DISM.exe /Online /Cleanup-Image /RestoreHealth
- Press Enter and wait for the operation to finish.
Do not close the window while DISM is working. The command repairs the Windows component store, which is the source Windows uses for protected system-file repairs.
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3. Run SFC immediately afterward
In the same elevated Command Prompt, enter:
sfc /scannow
Press Enter and let the scan reach 100 percent. Then restart Windows and retry the program that produced the error.
A successful result normally says that Windows Resource Protection found no integrity violations, or that it found corrupt files and repaired them. If the affected application now opens, the repair worked.
For Microsoft’s documented procedure, see Using System File Checker in Windows.
Repeating DISM and SFC without knowing what changed can make troubleshooting slow. Outbyte PC Repair provides a free scan that shows detected problems, while repair actions are handled by the full version; it is optional, and Windows repair remains the appropriate fix for this Microsoft component.
Fix 2: Check the file path and Microsoft signature
A file named synchostps.dll is not automatically trustworthy. The expected copy belongs under the Windows directory, not beside an unrelated application or in a user-writable folder such as Downloads or AppData.
Check the normal locations
- Press Windows key + E.
- Click the address bar.
- Enter:
%SystemRoot%System32
- Press Enter.
- Search for
SyncHostps.dll.
On 64-bit Windows, also check:
%SystemRoot%SysWOW64
System32 contains 64-bit system files on 64-bit Windows. Despite its name, SysWOW64 contains 32-bit system files. Do not swap files between these folders.
Check the digital signature
- Right-click the file.
- Select Properties.
- Open the Digital Signatures tab.
- Select the Microsoft signature and click Details.
- Confirm that Windows reports the signature as valid.
You can also check the usual 64-bit location in PowerShell:
Get-AuthenticodeSignature "$env:windirSystem32SyncHostps.dll"
A valid Microsoft signature is reassuring, but it does not by itself prove that the file is healthy or located correctly. A copy outside the Windows directory, an invalid signature, or a file that appeared after an unknown installer deserves further investigation.
Do not delete a suspicious file before recording its full path and checking your security software. Removing a protected Windows file manually can create another failure.
Fix 3: Check antivirus quarantine and scan for malware
Security software can quarantine a damaged file, a falsely detected file, or a modified copy. The correct response depends on what was detected.
- Open Windows Security from Start.
- Select Virus & threat protection.
- Click Protection history.
- Look for an event involving
SyncHostps.dll. - Read the detection name, path, and action taken.
Restore the file only when you have confirmed that it is a genuine Microsoft copy from the Windows system directory and the detection is a false positive. If the file was in an application folder, a temporary folder, or another unexpected location, do not restore it automatically.
Instead:
- Return to Virus & threat protection.
- Select Scan options.
- Run a Full scan.
- If the problem continues or malware is suspected, run Microsoft Defender Offline scan.
After the scan, run DISM followed by SFC again. Malware remediation can leave protected files damaged, and Windows servicing is safer than copying a replacement DLL.
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If the message appears only when one application starts, repair that application after repairing Windows. The application may be loading a wrong local copy, or the message may identify a missing dependency rather than prove that synchostps.dll itself is absent.
Use the application’s own installer or its Windows repair option:
- Open Settings → Apps → Installed apps.
- Find the affected application.
- Click the three-dot menu beside it.
- Select Advanced options, if available.
- Choose Repair and retry the application.
- If Repair does not help, choose Reset only if you understand that it may remove local app data.
- If neither option exists, uninstall the application.
- Restart Windows.
- Reinstall it from the developer’s official installer or Microsoft Store listing.
Do not copy a DLL downloaded from a search result into the application directory. A program may require a particular architecture or a different dependency, and an arbitrary file can introduce a second mismatch.
If the application is old, right-click its shortcut, select Properties → Compatibility, and test an appropriate compatibility mode only after the Windows repair steps. This changes how the program runs; it does not repair the system DLL.
Do these 3 things before closing this tab:
1Scan for outdated or missing drivers - takes under a minute2Clear out junk files and repair common Windows errors3Fix the driver behind crashes, sound loss and screen glitchesFix 5: Investigate architecture and dependency errors
Windows can display “The specified module could not be found” even when the named DLL is present. The missing item may be a dependency that Windows could not load.
Check the affected program’s architecture with its documentation or installer. On 64-bit Windows:
- 64-bit Windows components normally use
System32. - 32-bit Windows components normally use
SysWOW64. - A 32-bit application can fail if it receives a 64-bit DLL, and the reverse is also true.
Do not copy the 32-bit file into System32 or the 64-bit file into SysWOW64. Repairing Windows with DISM and SFC preserves the correct architecture.
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The same caution applies to Visual C++, DirectX, and .NET. synchostps.dll is a Windows component, not verified as a Visual C++ Redistributable, DirectX, .NET, or game-runtime file. Install a runtime only when the affected application’s official documentation or installer specifically identifies it as missing.
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Fix 6: Do not use Regsvr32 as a routine repair
A common suggestion is:
regsvr32 synchostps.dll
That is not a general fix for this error. regsvr32 calls a DLL’s registration entry point; it does not restore a missing file, repair a corrupted component store, or fix an architecture mismatch. Proxy and stub files can have registration-related exports without requiring manual registration during normal Windows operation.
Use Regsvr32 only when the software vendor or Microsoft specifically instructs you to register that exact file. Otherwise, use DISM and SFC.
Microsoft documents the command’s purpose in regsvr32.
Fix 7: Update drivers only when the error points to a device
synchostps.dll is not identified as a device driver. Do not install random drivers merely because a DLL error appears. If the message occurs while using a printer, camera, storage device, or another peripheral, update that device through its manufacturer or Windows Update.
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To check Windows-managed drivers:
- Right-click Start.
- Select Device Manager.
- Expand the relevant device category.
- Right-click the device.
- Choose Update driver.
- Select Search automatically for drivers.
- Restart Windows if a driver is installed.
Outbyte Driver Updater can scan for outdated drivers and show which versions need attention, while installation is handled by the full version; use it only as an optional aid, since a driver update is not the definitive fix for a damaged Windows DLL.
If DISM or SFC cannot repair the file
If SFC reports that it found corrupt files but could not repair some of them:
- Restart Windows.
- Run DISM again.
- Run
sfc /scannowagain. - Review:
%windir%LogsCBSCBS.log
If DISM cannot obtain repair files from Windows Update, use a matching Windows installation source. The source must correspond to the same Windows version and build family:
DISM.exe /Online /Cleanup-Image /RestoreHealth /Source:\<server>c$Windows /LimitAccess
Do not guess the source path or use an unrelated Windows installation.
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If repair still fails, use System Restore:
- Open Start and search for Create a restore point.
- Open it.
- Click System Restore.
- Select a restore point from before the error began.
- Follow the wizard and restart.
Back up important files first. If no restore point works, perform an in-place Windows repair installation using official Microsoft installation media. A clean installation should be the last resort after backing up personal data.
Avoid standalone DLL downloads
Do not download synchostps.dll from a random DLL site and place it in System32, SysWOW64, or an application folder. The replacement may contain malware, have the wrong architecture, be from the wrong Windows build, or fail to match its dependencies. It also leaves the damaged Windows component store untouched.
The safe sources are Windows Update, DISM and SFC, System Restore, and official Microsoft repair media. If only one application is affected, the application’s official installer is the correct source for that application’s own files.
FAQ
Is synchostps.dll a real Windows file?
Yes. It is a Microsoft Windows system DLL with the description “Proxystub for sync host.”
What does “Proxystub for sync host” mean?
It describes a COM proxy/stub component used by Windows synchronization-related components. It is not normally a program that you launch directly.
Is synchostps.dll a Visual C++ or DirectX file?
No verified evidence supports that classification. It belongs to Windows, although an application can report the error while a dependency or local application file is also damaged.
Where should it be?
Usually under %SystemRoot%System32. On 64-bit Windows, the 32-bit counterpart may be under %SystemRoot%SysWOW64.
Why does the message say the module is missing when the file exists?
The named file may be present while one of its dependencies is missing, corrupted, or the wrong architecture. A “not designed to run on Windows” message can have the same causes.
Should I register it with Regsvr32?
Normally no. Run DISM followed by SFC instead, unless a specific Microsoft or application instruction requires registration.
What if the error returns after repair?
Check antivirus quarantine, verify the signature and path, repair the application that triggers the message, and inspect CBS logs if SFC repeatedly reports unrepaired corruption. Persistent failures may require System Restore or an in-place Windows repair installation.
Quick Recap
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