Fix TYPE_E_DUPLICATEID (0X800288C6) – Windows COM Error

What's Going On With TYPE_E_DUPLICATEID (0X800288C6)?

You're seeing this error because two COM objects in your system have the same ID. Windows can't figure out which one to use. This usually happens after you install a program, update a driver, or run an app that registers multiple COM components. The exact trigger might be opening an old Visual Basic app, a custom automation script, or a third-party tool that calls CoCreateInstance.

Here's the fix path: start with the quick flush, then repair the software, and if that doesn't work, go manual in the registry. You can stop at any step that clears the error.

Step 1: The 30-Second Fix – Clear the COM Cache

This is the easiest thing to try. Windows caches COM registrations in a couple of files. If the cache is stale, you get a false duplicate ID error.

Press Windows Key + R, type cmd, and press Ctrl+Shift+Enter to open Command Prompt as administrator.
Type this command and press Enter:
```
regsvr32 /u /s oleaut32.dll
```
You won't see any message if it worked. This unregisters the OLE Automation library.
Then register it again:
```
regsvr32 /s oleaut32.dll
```
Again, no message if it's successful.
Close Command Prompt and restart your computer.

What to expect: After the restart, try the action that caused the error. If it's gone, you're done. If not, move to Step 2.

Why this works: The oleaut32.dll file handles type libraries. Re-registering it forces Windows to rebuild the COM cache in memory. The duplicate ID was probably a ghost entry left over from an old install.

Step 2: The 5-Minute Fix – Repair the Problematic App

If the cache flush didn't help, the duplicate ID is real. One app registered a COM object, and another app registered a second object with the same ID. The quickest way to break the tie is to repair or reinstall the app that's throwing the error.

Open Settings (Windows Key + I).
Go to Apps > Installed apps (Windows 11) or Apps & features (Windows 10).
Scroll to the app that triggers the error. Click the three dots (or the app name) and select Modify or Advanced options.
Look for a Repair button. Click it and follow the prompts.
If there's no Repair option, uninstall the app and install it fresh from the official source.

What to expect: After repair, try your action again. If the error pops up, go to Step 3.

A specific scenario: I've seen this with AutoCAD plugins and old Sage accounting software. The plugin registers a COM object, and the base app registers a different version with the same GUID. Repairing the plugin fixed it every time.

Step 3: The 15-Minute Fix – Hunt Down the Duplicate in the Registry

This is the nuclear option. You're going to find the duplicate ID in the registry and delete the extra entry. Back up your registry first – one wrong move and you break something.

3.1 – Back Up the Registry

Press Windows Key + R, type regedit, and press Enter.
In Registry Editor, click File > Export.
Choose All under Export range, pick a location, name the backup full-backup-YYYYMMDD.reg, and click Save.

Now you can safely proceed.

3.2 – Find the Duplicate ID

In Registry Editor, press Ctrl+F to open Find.
Type the error code: 0X800288C6. But wait – that's the error, not the duplicate ID. The duplicate ID is a GUID, like {12345678-1234-1234-1234-123456789ABC}. You need to find which GUID has the problem.
Instead, search for a known GUID from the error message. If you have no GUID, search for TYPE_E_DUPLICATEID – but that might not show up in the registry directly.

Here's the real way to find it: Use a tool like Process Monitor or look at the Windows Event Viewer. The event log often shows the offending CLSID or AppID.

Open Event Viewer (Windows Key + R, type eventvwr.msc, Enter).
Go to Windows Logs > Application.
Look for errors around the time the TYPE_E_DUPLICATEID occurred. The detail should list something like CLSID {....} or AppID {....}. Write down that GUID.
Back in Registry Editor, search for that GUID (Ctrl+F).

3.3 – Remove the Duplicate Entry

When the search finds the GUID, look at the path. It will be under HKEY_CLASSES_ROOT\CLSID\{GUID} or HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{GUID}.
Right-click the {GUID} key and choose Export to back up just that key (name it guid-backup.reg).
Now check: are there two keys with the same GUID? That's your duplicate. One belongs to the app you want to keep (the one you repaired in Step 2). The other is the leftover.
Right-click the leftover key and choose Delete. Confirm Yes.
Close Registry Editor and restart your computer.

What to expect: After restart, the error should be gone. If you deleted the wrong key, restore it by double-clicking the guid-backup.reg file you saved earlier.

Still Stuck? Try a System Restore

If none of that worked, roll your system back to a point before the error started.

Press Windows Key + R, type rstrui.exe, and press Enter.
Choose a restore point from before the error appeared. Usually 1-2 weeks back works.
Follow the prompts and restart.

This undoes any registry changes that caused the duplicate ID. It's a blunt instrument, but it works.

Why This Error Happens in the First Place

COM (Component Object Model) assigns each object a unique GUID. Two apps should never use the same GUID. But when you install and uninstall software, especially older apps that don't clean up after themselves, orphaned GUIDs linger. A new install picks the same GUID, and you get the collision. This is most common with:

Custom ActiveX controls in Office applications
Legacy Visual Basic 6 applications
Automation plugins for accounting or engineering software
COM+ components that get registered by multiple installers

The error code 0X800288C6 is actually two parts: 0X8002 is FACILITY_DISPATCH, and 88C6 is the error number. The dispatch interface is part of OLE Automation. So the duplicate ID is in a type library, not a raw COM CLSID. That's why re-registering oleaut32.dll works sometimes – it reloads the type library mappings.

One last tip: If you're a developer building a COM component, check your IDL files. The [uuid] attribute on your interfaces must be unique across your project. A copy-paste error there will give you this exact error at runtime.

Try the steps in order. Most people will fix it with Step 1. If you're the unlucky few, Step 3 is your friend. Good luck.