File directory not synchronized - synfs after mssparkutils.fs.mount

Hi dbeavon3,

You’re not imagining it - the /synfs path you get back from mssparkutils.fs.getMountPath(...) is an eventually-consistent projection of OneLake into the notebook’s file system. When you add or rename files outside the running Spark session (e.g., via the Lakehouse UI, another job, or upload), it can take a while before the mount’s directory listing catches up. That’s why your open("/synfs/notebook/.../Partition.xml") failed for several minutes and then “magically” started working.

Two workarounds:

1. Refresh the mounts before you read
   

   import mssparkutils
   mssparkutils.fs.refreshMounts()

   This forces the workspace/job mount metadata to resync so new files show up faster. See: Microsoft Spark Utilities docs and the refreshMounts reference notes here: Synapse mount API (same APIs).
2. (Better) Skip /synfs for reads and use an ABFSS path
   Read the file directly from OneLake instead of the mounted filesystem. With Python, use fsspec so you can call open() on ABFSS:

   import fsspec
   
   abfss_path = "abfss://<workspaceId>@onelake.dfs.fabric.microsoft.com/<LakehouseName>/Files/InventoryManagement/InventoryAgings/Partition.xml"
   with fsspec.open(abfss_path, "rb") as f:
       full_doc = f.read()

   This avoids the /synfs cache entirely. Nice walkthrough: Using fsspec with OneLake.

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