topic Re: Parameters FabricVariablesClient and FabricLakehouseClient in one udf function in Data Engineering

Parameters FabricVariablesClient and FabricLakehouseClient in one udf function

bruinsmm — Thu, 27 Nov 2025 13:34:10 GMT

When i use one UDF function with 2 parameters: myLakehouseDEV: fn.FabricLakehouseClient and var: fn.FabricVariablesClient i got and error, see below. When i use 2 UDF functions, one for FabricLakehouseClient and one for FabricVariablesClient, it works. Why can i not combine these parameters? A bug ?

Error message:

{

"functionName": "query_data",

"invocationId": "00000000-0000-0000-0000-000000000000",

"status": "Failed",

"errors": [

{

"errorCode": "WorkloadException",

"subErrorCode": "InternalServerError",

"message": "An internal execution error occured"

}

]

}

Source code:

@udf.connection(argName="myLakehouseTEST", alias="lhbronzesharedDEV")

@udf.connection(argName="var", alias="varlib")

@udf.function()

def query_data(myLakehouseTEST: fn.FabricLakehouseClient, var: fn.FabricVariablesClient) -> list:

connection = myLakehouseTEST.connectToSql()

cursor = connection.cursor()

cursor.execute(f"SELECT NAAM_NL, NAAM_EN FROM MDR.LAND WHERE LAND_ID = 142;")

rows = [x for x in cursor]

columnNames = [x[0] for x in cursor.description]

values = []

for row in rows:

item = {}

for prop, val in zip(columnNames, row):

item[prop] = val

values.append(item)

# Close the connection

cursor.close()

connection.close()

return values

Re: Parameters FabricVariablesClient and FabricLakehouseClient in one udf function

Mauro89 — Thu, 27 Nov 2025 16:43:49 GMT

Hi @bruinsmm,

have you used the defined aliases and checked if both connections are actually there?

Best regards!

Re: Parameters FabricVariablesClient and FabricLakehouseClient in one udf function

OnurOz — Thu, 27 Nov 2025 19:26:27 GMT

Hi @bruinsmm

this looks to me like an undocumented runtime limitation or a bug. Because I am getting the same error too.
However, in official github repository for the UDFs, I saw an example that requires that this works:

fabric-user-data-functions-samples/PYTHON/Warehouse/export_warehouse_data_to_lakehouse.py at main · microsoft/fabric-user-data-functions-samples

In the example above, I see two connections injected.

I suggest filing a bug to the team using this link: https://github.com/microsoft/fabric-user-data-functions-samples/issues

Hope that helps

Onur

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Re: Parameters FabricVariablesClient and FabricLakehouseClient in one udf function

OnurOz — Thu, 27 Nov 2025 20:20:22 GMT

I've dug more into this and identified a very weird behaviour. If I use FabricSQLConnection together with the FabricLakehouseClient it works. However If I use the FabricVariablesClient together with any of them, that is not working and throwing exactly the same internal error.

import fabric.functions as fn udf = fn.UserDataFunctions() @udf.connection(argName="variables", alias="varlib") @udf.function() def this_works(variables: fn.FabricVariablesClient )-> str: return variables.getVariables()["x"] @udf.connection(argName="variables", alias="varlib") @udf.connection(argName="myWarehouse", alias="fabWH") @udf.function() def this_fails(variables: fn.FabricVariablesClient, myWarehouse: fn.FabricSqlConnection, )-> str: return variables.getVariables()["x"] @udf.connection(argName="variables", alias="varlib") @udf.connection(argName="myLakehouse", alias="fablakehouse") @udf.function() def this_fails_too(variables: fn.FabricVariablesClient, myLakehouse: fn.FabricLakehouseClient, )-> str: return variables.getVariables()["x"]

Re: Parameters FabricVariablesClient and FabricLakehouseClient in one udf function

nielsvdc — Thu, 27 Nov 2025 22:09:05 GMT

Hi @OnurOz, it looks like this is unwanted behavior. Are you able to create a support request at Microsoft for this? I can also offer to help do this.

Re: Parameters FabricVariablesClient and FabricLakehouseClient in one udf function

bruinsmm — Fri, 28 Nov 2025 09:44:24 GMT

Hi @Mauro89 ,

If i use one function with FabricLakehouseClient and one function with FabricVariablesClient, it works. so the aliases are set up correctly.

Re: Parameters FabricVariablesClient and FabricLakehouseClient in one udf function

bruinsmm — Fri, 28 Nov 2025 09:46:40 GMT

Hi @OnurOz and @nielsvdc thanks for your help. I will pass the problem to my colleague who can contact with Microsoft.

Re: Parameters FabricVariablesClient and FabricLakehouseClient in one udf function

v-priyankata — Fri, 05 Dec 2025 10:50:57 GMT

Hi @bruinsmm
I hope you’ve submitted the support ticket. Once you receive a solution, please share it here so it can help others facing the same issue. If you have any further questions, feel free to reach out to the community.

Thanks.

Re: Parameters FabricVariablesClient and FabricLakehouseClient in one udf function

bruinsmm — Fri, 12 Dec 2025 10:37:45 GMT

Hi @nielsvdc Due to circumstances, we cannot submit this problem to Microsoft. Would you please submit this problem to Microsoft?

Re: Parameters FabricVariablesClient and FabricLakehouseClient in one udf function

nielsvdc — Fri, 12 Dec 2025 11:02:37 GMT

I have reported the issue under request ID 2512121420001293.

Re: Parameters FabricVariablesClient and FabricLakehouseClient in one udf function

bruinsmm — Fri, 12 Dec 2025 12:39:15 GMT

@nielsvdc thanks for your help

Re: Parameters FabricVariablesClient and FabricLakehouseClient in one udf function

nielsvdc — Tue, 16 Dec 2025 08:49:49 GMT

@bruinsmm @Mauro89

Thanks @OnurOz for the code. I had contact with someone from Microsoft team today and today the code worked in my tenant and theirs. So the issue seems fixed and it should now work in your environment.

Re: Parameters FabricVariablesClient and FabricLakehouseClient in one udf function

bruinsmm — Tue, 16 Dec 2025 09:17:16 GMT

@nielsvdc thanks. i have try the udf code. Now it works.