ERROR trying to import schema in ADF Copy Data activity Mapping tab (toLowerCase)

Question

All of my copy activities have been working fine and within the last 2 days if I try creating a new Copy data activity or edit an existing one and try to import schema from the Mapping tab I am getting the error:

Failed to import source schema. Cannot read properties of undefined (reading 'toLowerCase')

If I look at the developer tools in the browser it is showing the correct fields in the Response data. This error occurs with any data source I tried and with several copy activities I tried. Was there any changed to ADF that may have created a big?

Thanks.

J

Answer 1

Hi Juan Harrington,
Thank you for sharing the details. Based on the symptoms you described, this looks like a portal UI issue in Azure Data Factory Studio rather than a problem with your copy activity configuration or data sources.

The error “Failed to import source schema. Cannot read properties of undefined (reading ‘toLowerCase’)” typically occurs when the Mapping tab tries to process schema metadata returned by the service and one of the expected properties is null or undefined. Since you can already see the correct fields in the browser developer tools response, the backend is returning the schema successfully the failure is happening only when the Studio UI attempts to render it.

Because this started recently and reproduces across multiple sources and activities, it likely points to a recent Studio update/regression instead of anything changed in your pipelines.

As temporary workarounds, you can try the following:

Define mappings manually instead of using Import schema.

Open ADF Studio in an InPrivate/Incognito window or clear browser cache to make sure updated portal scripts load.

Try a different browser to rule out cached UI components.

If the schema was previously imported in another activity, consider duplicating that activity and adjusting it rather than re-importing.

Your existing copy activities should continue to run normally since the issue is limited to the Mapping tab schema import experience.
Hope this Helps! could you please let us know if you issue persists