Power Query Folding breaking query

jaryszek 

Because Folder.Files() (and similar M functions that reference local paths) are NOT supported in Power BI Service.

Power BI service (Fabric workspace) cannot access your local machine's file system like D:\... drive.
It expects:

• Cloud paths (SharePoint, OneDrive, Azure)

• Or properly parameterized Web.Contents() links

When you publish, Power BI tries to validate the data source path and cannot resolve your dynamic local path ➔ it hangs or errors.

Even hardcoded local paths sometimes cause issues — but with dynamic path, Power BI cannot even check or cache the path ahead of time, making it worse.

If you must use Folder.Files locally ➔ disable loading it in the service

You can:

• Wrap your local source logic inside an if block based on a parameter.

Example:
let
Source = if Environment = "Local"
then Folder.Files(Text.Combine({Text.Replace(paramLocalRepositoryPath, "/", "\\"), paramRepository}, "\\"))
else null
in
Source

You create a parameter called Environment with values "Local" or "Service".

This way ➔ When you publish, and Environment is "Service" ➔ it does NOT try to access local path, avoiding crash.

Switch to SharePoint, OneDrive, or Azure for file storage

If these files are important, move them to SharePoint Document Library or Azure Blob Storage, and connect via SharePoint.Files() or AzureStorage.DataLake().

Use a Dataflow / Lakehouse instead of direct local files

Instead of trying to pull files at report level ➔ you can use Dataflows or Fabric Lakehouses to land the files, then connect.
let
path = Text.Combine({Text.Replace(paramLocalRepositoryPath, "/", "\\"), paramRepository}, "\\"),
Source = if Environment = "Local" then Folder.Files(path) else #table({}, {})
in
Source

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