Getting error while refreshing Dataflow Gen2

[Suraj_1331]

I am using MS fabric for one of my customer. My source is On-Prem sql and sink is my warehouse within fabric, I am trying to fetch 6 tables using dataflow gen 2. Once Dataflow Gen2 got refresh, it refreshes 2 tables out of 6 tables and rest of the tables failing to refresh. After this whenever next refrresh happens alternatively 2 tables which is failed in first refresh got successful in next refresh. The same refresh operation simultaniously happening with different tables and ending with below error of Data flow Gen 2 refresh.

" Error Code: Mashup Exception Expression Error, Error Details: Couldn't refresh the entity because of an issue with the mashup document MashupException.Error: Failed to insert a table., InnerException: We cannot apply operator & to types Number and Record., Underlying error: We cannot apply operator & to types Number and Record. Details: Reason = Expression.Error;Message = We cannot apply operator & to types Number and Record.;Detail = [Operator = "&", Left = 2, Right = [...]];Message.Format = We cannot apply operator #{0} to types #{1} and #{2}.;Message.Parameters = {"&", "Number", "Record"};Microsoft.Data.Mashup.Error.Context = System GatewayObjectId:  (Request ID: ). "

I believe this is not a problem with table, this is something else because every time 2 tables will get refreshed. i don't understand the reason. Kindly suggest any solution.

[supriyapandey19]

Hi, 

Did anybody find any solution to this?

Thanks

[jasiluka12]

i am getting exactly the same error.
looks like a nonsense as my advanced editor queries are super simple and there is no concatenation happening at all of any fields. as a matter of fact i am not even creating any new field. 

in my dataflow i have 2 queries and once i trigger it -> table A fails. If i trigger it another time , table B fails. This is a totally random error it seems and relates to something else.

PowerQuery loads fine and when mapping table(s) to data warehouse , all fields map just fine.

[jasiluka12]

to add to the topic: issue disappeared after changing data destination for each table from Warehouse to Lakehouse...

Feels like this is a bug when your destination is Warehouse.

[Anonymous · Accepted solution]

Hi @Suraj_1331 ,

The error message indicates an issue with the application of an operator to incompatible types (Number and Record), which suggests there might be a problem in the way certain expressions or transformations are defined within your dataflow.

Please check the steps:

Examine the transformations applied in your dataflow, especially focusing on any expressions that use the operator . This operator is typically used for string concatenation or bitwise operations, so ensure it's being used correctly in the context of your data types

Ensure that the data types of the columns involved in the transformations are compatible with the operations being performed.

I have also found a similar post, please refer to it to see if it helps you.

Solved: Re: Couldn't refresh the entity because of an issu... - Microsoft Fabric Community

What i do now is after updating Dataflow Gen2,

- i don't click click the Publish button right away,

- I click other tables first,

- close the Dataflow Gen2 to see the workspace again

- find the updated Dataflow Gen2

- wait for few minutes(1-5) because MS Fabric is slow in everything, i dont know if this is because im using Free Trial

- after waiting for few minutes, near the name of my dataflow gen 2 iclick the "Refresh now" button, the one that looks like circle

Best Regards
Community Support Team _ Rongtie

If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.