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MG86's avatar
MG86
Advocate II
2 years ago

Mashup engine error when refreshing Dataflow Gen 2 with Lakehouse as destination

I am struggling with the following, perhaps it's just a bug in a product that's in beta, but hopefully someone can help: I have created a Gen2 dataflow in which I get data from a REST/JSON Web API...
Dataflow
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gthill's avatar
gthill
Advocate I
2 years ago

I am struggling with a similar issue - MashupException.Error: Expression.Error: We can't convert values of this type to JSON. Details: Reason = Expression.Error

 

The Dataflow appears to be working fine in the editor, but when it is published and refreshed it fails with this error.

 

The Dataflow extracts data from Excel files via an ADLS Gen2 shortcut in the Lakehouse.

 

I've tried various data types, removing any spaces and special characters from column names, removing columns etc. but I'm out of ideas now and haven't been able to find a way to narrow this error down further - more details in the erorr message or a method to debug would be much welcomed.

 

Any suggested solutions please?

gthill's avatar
gthill
Advocate I
2 years ago

OK - so I created a new Dataflow and copied the M queries across from the one which is failing and this new one works fine.

 

I assume there is a bug or something corrupting the original Dataflow. 

 

Not an ideal solution, but might help others as a workaround until the root cause can be identified.