Fix COMADMIN_E_AMBIGUOUS_PARTITION_NAME (0x8011045D) in Minutes

What triggers this error — and the quick fix

You're deploying a COM+ application, editing partition properties in Component Services, or running a script that references a partition by name. Instead of success, you get COMADMIN_E_AMBIGUOUS_PARTITION_NAME (0x8011045D): "The partition name is not unique and cannot be resolved to a partition ID."

I know this error is infuriating because it stops everything. But here's the thing — nine times out of ten, the fix is dead simple: you've got two partitions with the same name. Windows can't tell which one you're pointing to.

The real fix: Find the duplicate and rename or remove it. Let me show you exactly how.

Cause #1: Duplicate partition names visible in Component Services

This is the most common culprit. Somewhere in your COM+ Partition list, a name appears twice. Could be from a failed migration, a sloppy script, or someone on your team creating partitions manually without checking first.

How to verify

1. Open Component Services (dcomcnfg from Run or Command Prompt).
2. Expand Console Root → Component Services → Computers → My Computer → COM+ Partitions.
3. Look at the list of partitions. If you see the same name twice — bingo.

How to fix

Right-click the duplicate partition and either Rename it to something unique or Delete it if it's not needed. Be careful — deleting a partition also removes any COM+ applications assigned to it. If you're not sure, just rename it to something like "Old_App_Partition" and test if the error goes away.

Once renamed or removed, restart the COM+ System Application service:

net stop "COM+ System Application" && net start "COM+ System Application"

Try your operation again. If the error clears, you're done. If not, move to the next cause.

Cause #2: Hidden duplicates in the COM+ registration database

Sometimes a duplicate partition name doesn't show up in Component Services. I've seen this happen after uninstalling a third-party app that left orphaned entries. The partition still exists in the registry but isn't visible in the GUI.

How to find hidden duplicates

You'll need to dig into the registry. Back up your registry first (regedit → File → Export). Then navigate to:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\COM3\PartitionTable

Look for keys like {GUID} with a value named Name. If you see two keys with the same Name value, you've found hidden duplicates.

How to fix

Note down the GUID of the partition you want to keep (the one that's in use). For the duplicate, delete its entire key under PartitionTable. I also recommend checking HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\COM3\PartitionInstall for leftover references with the same GUID — clean those out too.

Restart the COM+ System Application service again and test.

Cause #3: Name collision with the default partition

This one's sneaky. Windows creates a default partition named "Base Application Partition" or "Default Partition" depending on the version (Windows 10, Server 2016, Server 2019). If you create a partition with exactly the same name, even if it's not shown in the GUI as a duplicate, the COM+ system gets confused.

How to check

In Component Services, look at the COM+ Partitions list. The default partition is usually hidden. To see it, you need to enable viewing of hidden partitions:

1. Right-click COM+ Partitions → Properties.
2. Check Show all partitions (if available — some older versions don't have this).
3. If you see your custom partition name matching the default, rename yours.

If the option isn't there, use PowerShell:

$partitions = Get-COMObject "COMAdmin.COMAdminCatalog" | ForEach-Object { $_.GetCollection("Partitions") } ; $partitions.Populate() ; $partitions | Select-Object Name

This lists every partition including system ones. Look for a name like "Default" or "Base Application Partition". If yours matches, rename it:

$catalog = New-Object -ComObject COMAdmin.COMAdminCatalog
$partitions = $catalog.GetCollection("Partitions")
$partitions.Populate()
$partition = $partitions | Where-Object { $_.Name -eq "YourPartitionName" }
$partition.Name = "YourUniqueName"
$partitions.SaveChanges()

Restart the service afterward.

Quick-reference summary table

One last thing — if you're still stuck after all three, check your application's manifest or deployment script. I've seen developers hardcode a partition name that conflicts with one already in use. A rename on the script side fixes it just as well.

This error tripped me up the first time too, but now you know exactly where to look. Drop me a comment if you found a weird variant — I'm always learning.