Error with "Merge" Operation in (CDC) Copy Activity – System.Linq.Async Assembly Load Failure

[LorenzVe]

We are currently working with a client who has an on-premises database. To connect to this database from Azure, we set up a Self-hosted Integration Runtime on a VM using an Azure gateway.

Our objective is to set up a Copy job in Fabric, targeting a CDC table. However, when using the preview "Merge" feature as the sink behavior (instead of "Append"), we consistently receive the following error:

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Error message:

ErrorCode=FailedToUpsertDataIntoDeltaTable,'Type=Microsoft.DataTransfer.Common.Shared.HybridDeliveryException,Message=Hit an error when upsert data to table in Lakehouse. Error message: Could not load file or assembly 'System.Linq.Async, Version=6.0.0.0, Culture=neutral, PublicKeyToken=94bc3704cddfc263' or one of its dependencies. Reference assemblies should not be loaded for execution. They can only be loaded in the Reflection-only loader context. (Exception from HRESULT: 0x80131058),Source=Microsoft.DataTransfer.Connectors.LakehouseTableConnector,''Type=System.BadImageFormatException,Message=Could not load file or assembly 'System.Linq.Async, Version=6.0.0.0, Culture=neutral, PublicKeyToken=94bc3704cddfc263' or one of its dependencies. Reference assemblies should not be loaded for execution. They can only be loaded in the Reflection-only loader context. (Exception from HRESULT: 0x80131058),Source=Microsoft.DataTransfer.Connectors.LakehouseTableConnector,''Type=System.BadImageFormatException,Message=Cannot load a reference assembly for execution.,Source=,'

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Troubleshooting Steps Taken:

• We confirmed that the System.Linq.Async.dll file (v6.0.0.0) exists on the VM (although not in the GAC).

• We checked the GAC and could not find an appropriate folder. We unsuccessfully tried to do that manually.

• We also manually added version 6.0.3 of this assembly to the path:
  C:\Program Files\Microsoft Integration Runtime\5.0\Gateway

• Despite these changes, the error remains. 

• The VM is running Windows Server (fully updated) with .NET Framework 4.8 installed.

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Is there any idea on how to solve this? How does the folderstructure look like usually? Maybe its a completely different issue?

Any guidance would be appreciated.

Thanks and kind regards

[MG86]

Did you get a fix for this?

[v-sgandrathi]

Hi @LorenzVe,

Thank you for the detailed breakdown and the steps you've already taken.

Since this issue involves a deeper runtime dependency and relates to the preview Merge behavior in a CDC pipeline, it may require investigation from the product team. As you're on a Power BI Pro license, you're eligible to open a support ticket with Microsoft for direct assistance.

This will allow the support team to look at your environment specifics, integration runtime setup, and provide targeted help.

To raise a support ticket for Fabric and Power BI, kindly follow the steps outlined in the following guide:

How to create a Fabric and Power BI Support ticket - Power BI | Microsoft Learn

If this post helps, please give us Kudos and consider marking it Accept as solution to assist other members in finding it more easily.

Thank you for being a part of Microsoft Fabric Community Forum!

[LorenzVe]

Ok thank you for letting me know!

[v-sgandrathi]

Hi @LorenzVe,

You’re very welcome.

After you submit the support ticket, we would appreciate it if you could share any important updates or solutions in this thread. This information may assist other community members with similar issues.

We wish you a smooth resolution, and thank you for your continued participation in the Microsoft Fabric Community.

Regards,

Sahasra_CST Member.

[v-sgandrathi]

HI @LorenzVe,

We are following up regarding your query. Could you please confirm if the issue has been resolved through the support ticket with Microsoft?

If resolved, kindly share the resolution or key insights here to assist others in the community. If we don’t hear back, we will close this thread.

For further assistance, please reach out via the Microsoft Fabric Community Forum and create a new thread. We will be happy to help.

Thank you for your understanding and participation.

[lbendlin · Accepted solution]

Since you have a Pro license you can open a Pro ticket at https://admin.powerplatform.microsoft.com/newsupportticket/powerbi