Source data from Cognos (using ODBC) and load into Warehouse

[swetadutta7]

Hi all,

I am working on a very simple Gen2 CI/CD dataflow package to read cognos files and load it into DW.

I am able to establish connection using the existing ODBC connection (created on the server) and can view all the existing tables too but when trying to load it into a Warehouse table (without any transformation), it keeps failing and the error message isn't helping either (see below) 

There was a problem refreshing the dataflow. Please review the error message(s) below, fix the problem, and try again. (Request ID: 8de44e79-56fc-4bf8-b00f-e96e4de43099).

Error Details: We encountered an error during evaluation. Details: Unknown evaluation error code: 999999 (Request ID: 8de44e79-56fc-4bf8-b00f-e96e4de43099).

[v-hashadapu]

Hi @swetadutta7 , Hope you are doing well. Kindly let us know if the issue has been resolved or if further assistance is needed. Your input could be helpful to others in the community.

[v-hashadapu]

Hi @swetadutta7 , Hope you're doing fine. Can you confirm if the problem is solved or still persists? Sharing your outcome will help others in the community.

[v-hashadapu]

Hi @swetadutta7 , hope you are doing great. May we know if your issue is solved or if you are still experiencing difficulties. Please share the details as it will help the community, especially others with similar issues.

[burakkaragoz]

Hi @swetadutta7 ,

I’ve run into similar issues before when working with Gen2 dataflows and ODBC sources like Cognos. That error code 999999 is pretty vague, but it usually shows up when the engine hits something unexpected during evaluation. Especially when there’s no transformation step in the flow.

Here’s a few things you could try:

• Even if you don’t need to transform the data, just add a tiny step like renaming a column or filtering one row. It helps the engine lock in the schema before pushing to the Warehouse.
• Double-check the data types coming from Cognos. Some ODBC drivers expose types that don’t map cleanly to Fabric’s supported types.
• Also make sure the destination table in the Warehouse matches the source structure exactly. Even small mismatches can trigger evaluation errors like this.

If you can share more about the table structure or the types involved, happy to take a closer look.

If my response resolved your query, kindly mark it as the Accepted Solution to assist others. Additionally, I would be grateful for a 'Kudos' if you found my response helpful.

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[v-hashadapu]

Hi @swetadutta7 , Thank you for reaching out to the Microsoft Community Forum.

This usually happens when Power Query automatically infers column types from your ODBC source that don’t align with the schema of the target Warehouse table. Even if you aren’t applying transformations, mismatches, especially with datetime, null values or unsupported types like binary can cause the load to fail without a clear message. To resolve this, explicitly define the column types using Table.TransformColumnTypes or allow the dataflow to create a new table to avoid schema conflicts. If the issue continues, consider loading into a Lakehouse table first and then using a pipeline to move the data into the Warehouse. This gives more control and better visibility into any schema issues.

If this helped solve the issue, please consider marking it “Accept as Solution” so others with similar queries may find it more easily. If not, please share the details, always happy to help.
Thank you.