## TL;DR
Grant the identity that runs materialization read and write access on the offline bucket named in the error, and confirm the bucket name and project in the FileSource or BigQuery source config match the bucket the policy was set on, because the job cannot even list objects to start the load. Start with the Feast materialization job identity and the GCS offline bucket policy, work on one affected call, record, or run first, and prove the fix there before running the full set. Most cases clear once the cause named in step 2 is corrected at its source rather than retried unchanged.

```text
Feast materialize failed error "PermissionError: cannot list objects in GCS offline bucket"
```

## Use this when
- You see this exact message or symptom: Feast materialize failed error "PermissionError: cannot list objects in GCS offline bucket"
- One run, record, call, or object is affected and you can name it
- A retry without changing anything reproduces the same result

## Not for this skill when
- The system fails with a different message and none of the signals here appear
- Nothing has failed yet and you are doing first time setup or general planning
- Every service from this vendor is down for all users, which is a vendor outage to wait out first

## Steps
1. Reproduce the failure once using the Feast materialization job identity and the GCS offline bucket policy, and record the time, the workspace or account, and the one item it names. Verify: you have one failing item identified, not a similar older failure
2. Inspect the service account the materialization job runs as, the bucket IAM policy, and the bucket path in feature_store.yaml and the data source definition. Verify: you can point to the specific value, field, segment, or state that does not match what this operation needs
3. Apply the fix at that source: Grant the identity that runs materialization read and write access on the offline bucket named in the error, and confirm the bucket name and project in the FileSource or BigQuery source config match the bucket the policy was set on, because the job cannot even list objects to start the load. Verify: the corrected value or setting is visible in the system itself, not only in a local file or the agent notes
4. Re-run the original operation on the single affected item first. Verify: that one item completes with no trace of the failure described above, and the online and offline values for that entity agree
5. Check the downstream result a user or the next job would see, comparing it against the source for the same item. Verify: the downstream result agrees with the source in content and in timing
6. Repeat for the full set, watch the first few items in the same log you started from, and write the root cause and the changed setting into the run notes. Verify: the full run finishes, the notes name the failure and the fix, and no earlier item regressed

## Variant phrasings
### Feast materialize failed error "PermissionError: cannot list objects in GCS offline bucket"
The subject-first phrasing of the same failure. The fix is the same, start at step 1 and confirm the item the log or record names.
### Tool-first phrasing of this failure
The phrasing searchers use once they know which system raised it. It is the same underlying problem, not a separate bug.
### Why does this keep happening after a retry
The repeat-occurrence phrasing. A retry without the step 2 and step 3 checks almost always reproduces it, because the cause sits in the input, setting, or record state, not in the attempt.

Compatibility: Feast 0.36 or later, GCS offline store, materialization from Cloud Run, Airflow, or a VM job.

## Why it happens
Feast itself runs fine locally where your own credentials apply, which hides the problem until a scheduled job runs under a different, narrower identity. A list denial is the first call the job makes, so nothing partial is written.

## Provenance

Resolved from the public thread: https://vectle.com/posts/pst_Nn-3e9VIdhprrlhuN7fVcw