Fixing COMADMIN_E_COREQCOMPINSTALLED (0x80110435)

1. The Most Common Cause: A Conflicting DLL Registration

You'll see error 0x80110435 when trying to install or update a COM+ application — like an MSI package from a vendor or an in-house .NET service. The message says A component in the same DLL is already installed. What's really happening: the COM+ catalog finds a CLSID that's already registered under a different DLL path.

I see this most often when someone runs regsvr32 on a DLL, then later tries to install the COM+ app that expects that same component. Or when you're redeploying an updated version of an app and the old DLL is still lingering.

Fix: Unregister the Conflicting DLL

1. Open an Admin Command Prompt or PowerShell.
2. Find the DLL that's causing the conflict. The error usually doesn't tell you the exact path, but you can check the COM+ application's components in Component Services (dcomcnfg). Look for the component that's failing — it'll show the DLL path.
3. Unregister that DLL:
   

   regsvr32 /u "C:\Path\To\Offending\YourComponent.dll"

4. Now try your COM+ app install again. It should work.

If you don't know which DLL is the problem, use regedit and search for the CLSID in HKEY_CLASSES_ROOT\CLSID. Look at the InprocServer32 key — that's your DLL path. If there are multiple entries for the same CLSID under different DLLs, you've found the conflict.

One gotcha: The COM+ catalog caches component info. If unregistering doesn't fix it, restart the COM+ System Application service (COM SysApp) or reboot.

2. Orphaned COM+ Registration Entries

Sometimes a COM+ application gets partially uninstalled — maybe an MSI rollout failed, or someone manually deleted files. The COM+ catalog still holds onto the component registration, even though the DLL is gone. When you try to install the same component again (or a new version), the catalog sees the old entry and throws 0x80110435.

Fix: Remove the Orphaned Component from the COM+ Catalog

1. Open Component Services (run dcomcnfg).
2. Expand Component Services → Computers → My Computer → COM+ Applications.
3. Find the application that's failing. Right-click it and choose Properties.
4. Go to the Components tab. You'll see the offending component listed. Select it, click Remove, confirm.
5. Now reinstall the COM+ application.

If the component isn't visible in the GUI, try the command-line approach:

COMAdminCatalog catalog = new COMAdminCatalog();
ICatalogCollection apps = catalog.GetCollection("Applications");
apps.Populate();
// Iterate and find your app, then remove the component
// Or use the COM+ admin tool: %SystemRoot%\system32\com\comexp.msc /c

On older Windows Server (2008 R2 or earlier), I've also seen orphaned entries in HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\COM3\Applications. You can delete the entire application key there — but be damn sure that's the right app. Export first.

3. COM+ Application Partition Conflicts (Enterprise Deployments)

If you're in a domain environment with COM+ partitions, the error can pop up when a component with the same CLSID exists in a different partition. This is rare outside of large deployments with custom partition setups, but it bites people who copy COM+ apps between servers.

Fix: Check Partition Configuration

1. Open Component Services. Right-click My Computer → Properties → Options tab.
2. See if Enable COM+ Partitions is checked. If not, skip this section.
3. If it is enabled, go to Partitions under My Computer. Look for duplicate application names.
4. Remove the duplicate from the partition that shouldn't have it, or rename one of the apps.
5. Reboot the COM+ System Application service.

This one's tricky because the GUI doesn't always show which partition a component belongs to. Use PowerShell to list all partitions and their apps:

Get-WmiObject -Namespace root\Microsoft\COMPlus -Class COMSystemApplication | Select-Object Name, PartitionID

Compare the CLSID across partitions. If you find a match, delete the duplicate from the less important partition using COMAdminCatalog or by hand in the registry under HKLM\SOFTWARE\Microsoft\COM3\Partitions.

Quick-Reference Summary

Start with fix #1 — it's the culprit 80% of the time. If that doesn't work, move to the catalog cleanup. Partition issues? Only if you're running a partitioned setup. Skip the reinstall dance; this error is almost never fixed by a fresh install of the same app.