msaddndr.dll errors usually mean that an older Office add-in, Visual Basic 6 program, installer, or related developer tool cannot find the Microsoft Add-In Designer component it expects. The safest fix is to identify the program showing the error and repair or reinstall that parent application, rather than downloading the DLL and placing it in a Windows folder.
You may see one of these messages:
The program can't start because msaddndr.dll is missing from your computer.
Try reinstalling the program to fix this problem.
There was a problem starting msaddndr.dll.
The specified module could not be found.
Error loading msaddndr.dll.
The specified module could not be found.
The code execution cannot proceed because msaddndr.dll was not found.
Reinstalling the program may fix this problem.
msaddndr.dll is either not designed to run on Windows or it contains an error.
Try installing the program again using the original installation media
or contact your system administrator or the software vendor for support.
Some legacy installers instead report:
MSADDNDR.DLL does not exist or is not registered.
The 60-second answer
msaddndr.dll is a genuine Microsoft file named AddInDesigner. It belongs to the Microsoft Add-In Designer Object Library, a legacy COM and type-library component used by Visual Basic 6 software and older Microsoft Office COM add-ins.
It is not a normal Windows system DLL, DirectX file, .NET file, or Visual C++ Redistributable file. It is commonly associated with older Office and VB6 installations and may normally be located at:
C:Program FilesCommon FilesDesignerMSADDNDR.DLL
On 64-bit Windows, a 32-bit installation commonly uses:
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C:Program Files (x86)Common FilesDesignerMSADDNDR.DLL
Start with these steps:
- Note which application displayed the error.
- Repair or reinstall that application from its original installer.
- If Office is the parent application, run Office Repair.
- Check whether Windows Security quarantined the file.
- Register the genuine file only if the application requires registration.
- Use SFC and DISM only as fallback tools for broader Windows corruption.
Microsoft’s documentation describes Msaddndr.dll as the library that supports the IDTExtensibility2 interface used by Office COM add-ins. Microsoft’s Office 2010 file inventory lists the component for both 32-bit and 64-bit Office editions, with a documented package version of 6.01.9839 and a size of 99,992 bytes. Those details describe that Office package and do not make every copy found online interchangeable.
What is msaddndr.dll and what is AddInDesigner
The name refers to Microsoft Add-In Designer, not a general-purpose Windows runtime. The component provides type-library and COM support for older add-in architectures. Office COM add-ins use interfaces such as IDTExtensibility2 to connect an add-in to applications including Word, Excel, Outlook, and other Office programs.
Visual Basic 6 applications and third-party tools built against the Microsoft Add-In Designer library can also depend on it. That is why the error may appear when starting an old business application, an Outlook add-in, an installer, or a developer utility instead of when starting Office itself.
The file is published by Microsoft, but that does not mean it ships as a protected component of every Windows installation. There is no reason to expect a clean Windows installation to contain it unless an application installed it.
Microsoft’s legacy COM-add-in documentation covers the component in older Office environments. Microsoft also documents a compatibility limitation for custom add-ins that use interfaces in Msaddndr.dll: later Office distributions, including Office 2013-era installations, may not include or support the old component. If the problem began after an Office upgrade, treat it as a legacy add-in compatibility issue rather than assuming Windows deleted a system file.
First identify the program showing the error
The most important diagnostic fact is the application that displayed the message.
Check the title bar and the wording around the error. Ask:
- Did it appear while opening Outlook, Word, Excel, or another Office program?
- Did it appear while launching a VB6 application?
- Did it appear during installation or removal of an old program?
- Did it appear after an Office upgrade?
- Did antivirus software report a detection first?
- Does the error occur for one application or many?
If only one program reports the problem, repair that program first. If an old add-in reports it during Office startup, disable or remove the add-in after repairing the active Office installation.
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“Specified module could not be found” does not always mean that msaddndr.dll itself is absent. Windows can display that message when a dependency required by the DLL is missing or when the application is using the wrong architecture.
Fix 1: Repair or reinstall the parent application
This is the safest and most likely fix because the installer can restore the correct file, dependencies, COM registration, permissions, and architecture together.
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If the affected program is Microsoft Office
- Save your work and close all Office applications.
- Open Settings.
- Select Apps.
- Select Installed apps on Windows 11, or Apps & features on Windows 10.
- Find Microsoft 365 or Microsoft Office.
- Select the three-dot menu beside it.
- Select Modify.
- Choose Online Repair, then select Repair.
- Follow the prompts and restart Windows when the repair finishes.
An MSI-based Office installation may show a Repair option instead. Choose that option and complete the wizard.
Use Office Repair only when Office is the owning installation. It may not repair a third-party add-in that has its own installer. If the error returns after Office Repair, download or obtain the add-in’s installer from its software vendor and reinstall the add-in itself. For older software, use the original installation media when available.
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If the affected program is not Office
Use the program’s own maintenance option if it has one:
- Open Settings.
- Select Apps and then Installed apps.
- Select the affected program.
- Choose Modify, Repair, or Change if available.
- If no repair option exists, uninstall the program.
- Restart Windows.
- Reinstall it from the original vendor installer or installation media.
Do not uninstall a business application before confirming that you have its installer, license information, and any required data backup.
A successful repair should restore the file to the application’s expected location and recreate its registration if registration is part of the installation. If the same error remains, check whether the application is a 32-bit legacy program running on 64-bit Windows.
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1Repair Windows errors before they cause bigger problems2Fix the driver behind crashes, sound loss and screen glitches3Clear out junk files and repair common Windows errorsFix 2: Check the normal Designer folders
Use File Explorer to see whether the file exists in an expected installation folder:
C:Program FilesCommon FilesDesignerMSADDNDR.DLL
On 64-bit Windows, also check:
C:Program Files (x86)Common FilesDesignerMSADDNDR.DLL
Do not treat the presence of the file as proof that the installation is healthy. It may be unregistered, damaged, blocked, quarantined, the wrong architecture, or missing a dependency.
Do not copy the file to:
C:WindowsSystem32
merely because a generic DLL guide recommends that location. msaddndr.dll is normally an Office/VB6 Designer component, not a Windows system component. Moving it can cause the calling application to load an unintended copy and can make later repairs more difficult.
Fix 3: Check Windows Security quarantine
Antivirus software may have removed or quarantined a genuine file, especially if the parent application is old or the installation is unusual. Check the detection before reinstalling anything.
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- Open Windows Security from the Start menu.
- Select Virus & threat protection.
- Select Protection history.
- Review recent detections.
- Open an item that mentions
MSADDNDR.DLLor the affected application. - Check the file path and detection details.
- Restore the file only when it came from a trusted, verifiable installer and the detection is confirmed to be a false positive.
- If you restore it, reinstall or repair the parent application afterward if the error continues.
Do not simply turn off antivirus protection to make the error disappear. If the file came from an unknown download or an unofficial repackaged installer, remove that copy and obtain the application from its legitimate source instead.
Microsoft explains how Protection history records actions taken by Windows Security and why allowing an unsafe file can put the device at risk.
Fix 4: Register the genuine file when the error says it is not registered
Registration is relevant for msaddndr.dll because this is a COM/type-library component. It is not a universal solution for missing DLL messages.
Microsoft’s regsvr32 command calls the DLL’s DllRegisterServer entry point. Registration works only when the file implements the required COM registration functions. A registration failure can indicate the wrong architecture, a missing dependency, insufficient administrator permissions, or an incomplete installation.
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Register a 32-bit copy on 64-bit Windows
Most legacy Office and VB6 add-ins are 32-bit. On 64-bit Windows, open Command Prompt as administrator and run the 32-bit registration tool:
%windir%SysWOW64regsvr32.exe "C:Program Files (x86)Common FilesDesignerMSADDNDR.DLL"
To open an elevated Command Prompt:
- Open the Start menu.
- Type
Command Prompt. - Select Run as administrator.
- Paste the command.
- Press Enter.
The directory names are counterintuitive: SysWOW64 contains the 32-bit regsvr32.exe, while System32 contains the 64-bit version on 64-bit Windows.
Register the file on 32-bit Windows
Use:
%windir%System32regsvr32.exe "C:Program FilesCommon FilesDesignerMSADDNDR.DLL"
If Windows reports that the module could not be loaded, confirm the path first. If the file exists but registration still fails, do not download another copy. Repair or reinstall the parent application and verify whether the calling program is 32-bit.
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Fix 5: Address Office 2013 and later compatibility
If the error appeared after moving from an older Office release to Office 2013, Office 2016, Microsoft 365, or another newer distribution, the problem may be that the old add-in architecture is no longer included or supported.
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Microsoft’s legacy documentation identifies compatibility limitations for custom add-ins that use interfaces in Msaddndr.dll. The old Add-In Designer model is associated with Office XP, Office 2003, and Office 2007 documentation. A newer Office installation may therefore leave an old COM add-in without the component it expects.
Use this order:
- Identify the add-in or application that reports the error.
- Check whether its vendor provides an updated version.
- Install the vendor’s compatibility update or prerequisite if one exists.
- Confirm whether the add-in supports the bitness of installed Office.
- Repair Office only if Office itself is damaged.
- Remove obsolete add-ins that are no longer needed.
Office 32-bit and 64-bit editions are not interchangeable for every legacy add-in. A 32-bit add-in may fail in 64-bit Office even when Windows itself is 64-bit. Installing a random 64-bit DLL will not convert a 32-bit add-in into a compatible 64-bit application.
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If the vendor has abandoned the add-in, the durable solution may be replacing it, using a supported version of the parent program, or running the old software in an environment approved by the software vendor. Do not alter Office registry entries blindly to force an unsupported add-in to load.
Fix 6: Use Windows repair commands only for broader corruption
SFC and DISM are useful when several Windows components are failing, Windows servicing is damaged, or an installer cannot run correctly. They normally do not recreate an Office Designer component that belongs to an application installation.
Run DISM first from an elevated Command Prompt:
DISM.exe /Online /Cleanup-Image /RestoreHealth
Then run:
sfc /scannow
Exact steps:
- Open the Start menu.
- Type
Command Prompt. - Select Run as administrator.
- Run the DISM command.
- Wait for it to finish.
- Run
sfc /scannow. - Wait until verification reaches 100 percent.
- Restart Windows.
- Repair the parent Office or VB6 application again if necessary.
If SFC reports that it repaired files, restart and test the original application. If it reports that it could not repair some files, repeat the application repair rather than copying msaddndr.dll into a system directory.
When repeatedly hunting through Windows components and rerunning SFC or DISM makes it difficult to see what changed, Outbyte PC Repair can scan for reported system issues; its free scan shows what it found, while repair is performed by the full version. It is optional, and it does not replace reinstalling the specific Office add-in or application that owns msaddndr.dll.
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Use System Restore only when the program worked previously, a suitable restore point exists, and you understand that restoring can affect recently installed applications and drivers.
Fix 7: Update drivers only when the evidence points to a driver problem
A missing msaddndr.dll error is not normally a driver problem. Device Manager will not restore an Office or VB6 Designer component. Check drivers only if the same failure began after a hardware change, Windows reports device errors, or the application’s installer cannot access required hardware.
To check Device Manager:
- Right-click the Start button.
- Select Device Manager.
- Look for a yellow warning icon.
- Expand the relevant category, such as Display adapters, Sound, video and game controllers, or System devices.
- Right-click the affected device.
- Select Update driver.
- Select Search automatically for drivers.
- Restart Windows if a driver is installed.
Do not remove a device driver simply because msaddndr.dll is missing. First repair the application that requested the DLL.
If several devices need attention, Outbyte Driver Updater can scan for outdated drivers; its free scan identifies reported driver issues, while installation is handled by the full version. It is optional, and updating drivers is not a substitute for repairing the Office, VB6, or third-party application that depends on msaddndr.dll.
Should you download msaddndr.dll manually
No. Random DLL download sites are risky because the file may contain malware, have the wrong architecture, be an incompatible version, lack its dependencies, or be modified. Even a clean copy may not fix the COM registration or the parent application that requested it.
Do not:
- download a replacement from an unverified DLL site;
- copy it into
System32orSysWOW64without an application-specific instruction; - replace a quarantined file with an unknown copy;
- assume a 64-bit Windows installation needs a 64-bit DLL;
- install DirectX, .NET, or Visual C++ Redistributables solely because this file is missing;
- use registry cleaners to remove or recreate COM entries.
The safe sources are the original Office installer, the original VB6 or third-party application installer, a vendor-provided compatibility package, or an official Microsoft repair process. Microsoft’s Office documentation can confirm the file’s role and package history, but it does not make a downloaded standalone copy a supported replacement.
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How to distinguish the common causes
| Symptom | Most likely cause | Best next step |
|---|---|---|
| Error appears when one old program starts | Incomplete or damaged application installation | Repair or reinstall that program |
| Error appears during Office startup | Legacy COM add-in or Office installation problem | Disable the add-in, repair Office, then reinstall the add-in |
| Error began after an Office upgrade | Unsupported legacy add-in or missing compatibility component | Check for a vendor update and Office bitness support |
| File exists but message says not registered | Missing COM registration | Register the genuine, architecture-matched file |
| File disappeared after antivirus action | Quarantine or removal | Review Protection history and verify the installer source |
| Several Windows components fail | Broader Windows corruption | Run DISM, then SFC |
| Registration says the module cannot be loaded | Wrong architecture or dependency failure | Repair the parent application and verify 32-bit versus 64-bit requirements |
Frequently asked questions
Is msaddndr.dll part of Windows
No verified evidence establishes it as a Windows-protected system component. It is associated with Microsoft’s Add-In Designer Object Library and older Office and VB6 software. A normal Windows installation does not necessarily contain it.
Is msaddndr.dll a virus
The filename belongs to a genuine Microsoft component, but a filename alone does not prove that a particular copy is authentic. Check its location, publisher information, installation source, and Windows Security history. A copy from an untrusted download should not be registered.
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Does it belong to Visual C++, DirectX, or .NET
No. Do not install those packages solely to restore this file. The documented role is legacy Office/VB6 COM and type-library support.
Do I need the 64-bit version on 64-bit Windows
Not necessarily. The calling application determines the required architecture. Many legacy Office and VB6 programs are 32-bit and require the 32-bit registration context, even on 64-bit Windows.
Should I run regsvr32
Only after confirming that the genuine file is present and the application expects COM registration. Use the architecture-matched tool. regsvr32 is not a general-purpose repair command for every missing DLL.
Why does the error say “specified module could not be found” when the file exists
A dependency may be missing, the file may be damaged, the process may be using the wrong architecture, or the COM registration may be incomplete. Repairing the parent application is safer than replacing the visible file.
Will Office Repair fix a third-party add-in
It can restore an Office-owned component, but it may not repair a third-party add-in with its own installer. If the add-in still fails, repair or reinstall the add-in from its vendor’s original package.
Should I use Windows Features to install it
No Windows Feature is established as the distributor of msaddndr.dll. Windows Features are not the normal installation path for the Add-In Designer component.
Does this file belong to a game
There is no established connection between msaddndr.dll and a mainstream game runtime. If a particular game bundled the file, use that game’s own repair or verify-files function. Otherwise, identify the non-game program that actually displayed the error.
What is the definitive fix
Restore the component through the application that owns it. For Office, use Office Repair and then address the specific legacy add-in. For a VB6 or third-party program, use its original installer or a vendor-provided compatibility package. Only register the file manually when the application requires it and the file is trusted.
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