Unable to use readnextasync on feediterator in Version 3.45.2, getting error: unable to load assembly system.diagnostics.diagnosticsource 8.0.0.0

[Chays21]

We are continuously addressing and improving the SDK, if possible, make sure the problem persist in the 3.45.2.

Describe the bug
FeedIterator.ReadNextAsync method throws System.IO.IO for System.Diagnostics.DiagnosticSource 8.0.0.0. however I did not face this issue with older version 3.40.0.

To Reproduce
Create a function app project that runs in process functions, targeting framework net 6.0. Install Microsoft.Azure.Cosmos 3.45.2. Create a Cosmos Client and container. try with the below code.

Expected behavior
ReadNextAsync should not throw this exception

Actual behavior
FeedIterator.ReadNextAsync method throws System.IO.IO for System.Diagnostics.DiagnosticSource 8.0.0.0

Environment summary
SDK Version: Microsoft.NET.SDK.Functions 4.2.0
OS Version (e.g. Windows, Linux, MacOSX) : Windows

Additional context
Add any other context about the problem here (for example, complete stack traces or logs).

Package references in my project:

Exception details:

[Pilchie]

Can you include the rest of ex.Message and ex.StackTrace?

[sourabh1007]

I am not sure why you are getting error for 8.0.0 version but for your information, In SDK 3.45.0, We upgraded to System.Diagnostics.DiagnosticSource 8.0.1 version.

Can you please make sure, DiagnosticSource library is getting loaded correctly with cosmosdb SDK

[threedot14]

We are experiencing practically the same problem. (Our failure is on an UpsertAsync. not ReadNextAsync.)
The Full error message for us

Could not load file or assembly 'System.Diagnostics.DiagnosticSource, Version=8.0.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51'. Could not find or load a specific file. (0x80131621)

We tested the recent release versions one by one, and all else being equal:

• 3.40.0 (confirmed by OP), 3.43.0. 3.44.0, and 3.44.1 work. We have locked in the version at 3.44.1 as a workaround for now.
• 3.45.0, 3.45.2, 3.46.0 do not work

I submit that it is not the user's responsibility to provide the correct version of DiagnosticsSource to Cosmos sdk, because our programs do not have a direct dependency to DiagnosticsSource. There is some problem when 3.45.0 was released, that introduced the dependency issue, because 3.44.1 works for us all else being equal.

[Pilchie]

Can you include the callstack of the exception so that we can see what is trying to load the 8.0.0.0 version?

[supereddie]

We run into the same issue. Callstack:

System.IO.FileNotFoundException:
   at Microsoft.Azure.Cosmos.Telemetry.OpenTelemetryRecorderFactory.CreateRecorder (Microsoft.Azure.Cosmos.Client, Version=3.46.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35)
   at Microsoft.Azure.Cosmos.ClientContextCore+<RunWithDiagnosticsHelperAsync>d__40`1.MoveNext (Microsoft.Azure.Cosmos.Client, Version=3.46.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35)
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw (System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
   at Microsoft.Azure.Cosmos.ClientContextCore+<OperationHelperWithRootTraceAsync>d__30`1.MoveNext (Microsoft.Azure.Cosmos.Client, Version=3.46.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35)
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw (System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
   at *my code*
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw (System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
   at *my code*
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw (System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
   at *my code*
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw (System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
   at *my code*
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw (System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Private.CoreLib, Version=6.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e)
   at *my code*

[threedot14]

I am not sure why you are getting error for 8.0.0 version but for your information, In SDK 3.45.0, We upgraded to System.Diagnostics.DiagnosticSource 8.0.1 version.

Can you please make sure, DiagnosticSource library is getting loaded correctly with cosmosdb SDK

#4810 upgraded to DiagnosticSource@8.0.1 and OpenTelemetry@1.9.0, which uses DiagnosticSource 8.0.0.
Is this the source of conflict for those of us who don't have a direct dependency to DiagnosticSource?

[manvkaur]

Running into the same issue, pinning to package 3.44.1 for now as a workaround.

[Pilchie]

@kirankumarkolli - can we get someone to try to repro and investigate this?

[manvkaur]

Got the fix for it, Azure Function In-Proc needs to be updated to dotnet 8 as Microsoft.Azure.Cosmos > 3.44.1 requires System.Diagnostics.DiagnosticSource >= 8.0.0.0. That dependency will only work in .NET in-proc 8.

Here is the documentation to update an app to dotnet 8 - In-Process Model - Updating to target .NET 8.

Also, its recommended to move to isolated worker model as beginning 10 November 2026, the in-process model for .NET apps in Azure Functions will no longer be supported.

[threedot14]

We have also gotten past the issue -- our library was cross compiling for net6 and net8 at the same time.
We have since removed net6 (about to be end-of-life in a couple months), and just leaving net8. And we are able to upgrade past 3.44.1 again.