"Over release of MOW - COM" assert in COM wrappers

  Discovering: LibraryImportGenerator.Tests (method display = ClassAndMethod, method display options = None)
  Discovered:  LibraryImportGenerator.Tests (found 162 of 165 test cases)
  Starting:    LibraryImportGenerator.Tests (parallel test collections = on [2 threads], stop on fail = off)
Assertion failed: (!"Over release of MOW - COM") (/__w/1/s/src/coreclr/interop/comwrappers.cpp: Release: 519)

https://github.com/dotnet/runtime/pull/122407/checks?check_run_id=57752025260

Known Issue Error Message

Fill the error message using step by step known issues guidance.

{
  "ErrorMessage": "Over release of MOW - COM",
  "ErrorPattern": "",
  "BuildRetry": false,
  "ExcludeConsoleLog": false
}

Known issue validation

Build: 🔎
Result validation: ⚠️ Validation could not be done without an Azure DevOps build URL on the issue. Please add it to the "Build: 🔎" line.
Validation performed at: 12/11/2025 3:35:19 PM UTC

Report

Build	Definition	Test	Pull Request
1228887	dotnet/runtime	LibraryImportGenerator.Tests.WorkItemExecution	#121679
1228892	dotnet/runtime	LibraryImportGenerator.Tests.WorkItemExecution	#122211
1228819	dotnet/runtime	LibraryImportGenerator.Tests.WorkItemExecution	#122414
1228776	dotnet/runtime	LibraryImportGenerator.Tests.WorkItemExecution	#122466
1228768	dotnet/runtime	LibraryImportGenerator.Tests.WorkItemExecution	#121513
1228677	dotnet/runtime	LibraryImportGenerator.Tests.WorkItemExecution	#122463
1228706	dotnet/runtime	LibraryImportGenerator.Tests.WorkItemExecution
1228445	dotnet/runtime	LibraryImportGenerator.Tests.WorkItemExecution	#119352
1228658	dotnet/runtime	LibraryImportGenerator.Tests.WorkItemExecution	#122460
1228403	dotnet/runtime	LibraryImportGenerator.Tests.WorkItemExecution	#122023
1228505	dotnet/runtime	LibraryImportGenerator.Tests.WorkItemExecution	#122441
1228500	dotnet/runtime	LibraryImportGenerator.Tests.WorkItemExecution	#122425
1228442	dotnet/runtime	LibraryImportGenerator.Tests.WorkItemExecution	#122430
1228180	dotnet/runtime	LibraryImportGenerator.Tests.WorkItemExecution	#122453
1228338	dotnet/runtime	LibraryImportGenerator.Tests.WorkItemExecution	#119575
1228311	dotnet/runtime	LibraryImportGenerator.Tests.WorkItemExecution	#121305
1228190	dotnet/runtime	LibraryImportGenerator.Tests.WorkItemExecution	#122454
1228146	dotnet/runtime	LibraryImportGenerator.Tests.WorkItemExecution	#122381
1228140	dotnet/runtime	LibraryImportGenerator.Tests.WorkItemExecution	#122407
1228125	dotnet/runtime	LibraryImportGenerator.Tests.WorkItemExecution	#122450
1228102	dotnet/runtime	LibraryImportGenerator.Tests.WorkItemExecution	#122448
1228170	dotnet/runtime	LibraryImportGenerator.Tests.WorkItemExecution	#122414
1228130	dotnet/runtime	LibraryImportGenerator.Tests.WorkItemExecution	#122451
1228078	dotnet/runtime	LibraryImportGenerator.Tests.WorkItemExecution	#122444

Summary

24-Hour Hit Count	7-Day Hit Count	1-Month Count
24	24	24

Tagging subscribers to this area: @dotnet/interop-contrib
See info in area-owners.md if you want to be subscribed.

@jkoritzinsky

/cc @jkoritzinsky

Likely caused by the test in this PR: #121643

update:

I think GetThis() with UniqueMarshalling on the receiving end is the culprit:

runtime/src/libraries/System.Runtime.InteropServices/tests/Common/ComInterfaces/IUniqueMarshalling.cs

Lines 22 to 29 in b500d44

    
           [GeneratedComClass] 
        
           internal partial class UniqueMarshalling : IUniqueMarshalling 
        
           { 
        
               int _data = 0; 
        
               public int GetValue() => _data; 
        
               public void SetValue(int x) => _data = x; 
        
               public IUniqueMarshalling GetThis() => this; 
        
           }

This is active in main right now, most builds hitting it. They don't always log the assertion, some just crash.

This build shows many failures - https://dev.azure.com/dnceng-public/public/_build/results?buildId=1227791&view=results

This mac failure has a dump report-- https://helixr1107v0xdeko0k025g8.blob.core.windows.net/dotnet-runtime-refs-heads-main-16db5125fb8a45fc8c/LibraryImportGenerator.Tests/1/coredump.50720.dmp.crashreport.json

Skip failing COM test (#122474)

Add AddRef to callee that caches interface ptr (#122509)

Navigation Menu

Repository navigation

"Over release of MOW - COM" assert in COM wrappers #122447

Known Issue Error Message

Known issue validation

Report

Summary

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

	[GeneratedComClass]
	internal partial class UniqueMarshalling : IUniqueMarshalling
	{
	int _data = 0;
	public int GetValue() => _data;
	public void SetValue(int x) => _data = x;
	public IUniqueMarshalling GetThis() => this;
	}

"Over release of MOW - COM" assert in COM wrappers #122447

Description

Known Issue Error Message

Known issue validation

Report

Summary

Activity

dotnet-policy-service commented on Dec 11, 2025

AaronRobinsonMSFT commented on Dec 11, 2025

jtschuster commented on Dec 11, 2025

ericstj commented on Dec 12, 2025

Metadata

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

Issue actions