DBFS folder access

DylanStout — Thu, 13 Mar 2025 14:22:21 GMT

When trying to open a folder in dbfs, mnt in my case, my whole team gets the following error message - Uncaught Error: No QueryClient set, use QueryClientProvider to set one.

Reloading the page results in this error not showing up anymore, but the folder keeps loading and doesn't open.

The mnt folder contains mounted storage containers.

When I use dbutils.fs.ls("dbfs:/mnt") it does show my files

Re: DBFS folder access

lingareddy_Alva — Thu, 13 Mar 2025 15:32:53 GMT

@DylanStout

Since dbutils.fs.ls("dbfs:/mnt") shows your files but the Databricks UI folder view keeps loading indefinitely, the issue likely stems from:

UI rendering issue
Large directory size or high file count
Latency in metadata retrieval
Permissions inconsistency

Recommended Steps to Resolve the Issue
1. Check Folder Size / File Count
The UI may struggle to render folders with thousands of files or deeply nested structures.
Solution: Use dbutils.fs.ls() in combination with len() to check file counts:
len(dbutils.fs.ls("dbfs:/mnt/<folder>"))
If the count is excessively high, consider partitioning or reorganizing files to improve UI responsiveness.

2. Verify Folder Permissions
Even if dbutils.fs.ls() works, the UI may fail due to missing read/list permissions in Unity Catalog or Storage ACLs.
Solution: Run the following to inspect permissions:
SHOW GRANTS ON STORAGE LOCATION '/mnt/<mount-point>';
If permissions are missing, add them:
GRANT READ ON STORAGE LOCATION '/mnt/<mount-point>' TO `<user/role>`;

3. Check for Mount Point Misconfiguration
An unstable or partially broken mount could cause this issue.
# Unmount (if already mounted)
dbutils.fs.unmount("/mnt/<mount-point>")
# Remount
dbutils.fs.mount(
source = "wasbs://<container>@<storage-account>.blob.core.windows.net/",
mount_point = "/mnt/<mount-point>",
extra_configs = {"<conf-key>":dbutils.secrets.get(scope="<scope>", key="<key>")}
)

4. Cluster Driver Overload / Memory Issue
UI delays can occur if the cluster’s driver node is overloaded.
Solution:
Restart the cluster.
If possible, increase the driver size (especially for metadata-heavy operations).

5. Force Refresh Metadata
Sometimes stale metadata can cause UI issues.
Solution: Run this command to force metadata sync:
ALTER TABLE <catalog>.<schema>.<table_name> REFRESH;

Re: DBFS folder access

DylanStout — Mon, 17 Mar 2025 12:05:46 GMT

Compute had to be assigned first before being able to open the folder, this was done automatically before.

The error is however not clear at all that this has to be done and that this is causing the error.

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