Fix Google Cloud Storage Authentication Errors — NetDrive

A render node has read G:\ from a Google Cloud Storage bucket for weeks, and this morning the drive won’t reconnect. Or a new teammate adds the bucket in NetDrive, signs in successfully, and sees an empty list. Both look like a NetDrive fault, but both usually trace back to the Google side: what the signed-in account is allowed to do, or whether Google still honors the authorization NetDrive holds.

Keep GCS buckets mounted and reachable

NetDrive lets Google Drive, OneDrive, S3, SFTP, WebDAV and more appear as native drives on Windows and macOS — no syncing, no full downloads.

• Mount a Google Cloud Storage bucket as a drive letter or volume
• Drive Manager shows connection status for every drive
• Reconnect a drive without changing its mount point

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Sort the symptom first

Authentication problems with GCS fall into two groups, and the fix differs for each.

• Sign-in itself fails or is rejected. The drive shows an authentication error, or the browser sign-in never completes. Suspect a revoked grant, a password or security change on the Google account, or stale saved credentials.
• Sign-in works but buckets are missing or access is denied. Google accepted the account, but the account lacks permission on the bucket. This is an IAM question, not a NetDrive one.

Check which group you are in before changing anything. Reconnecting the drive won’t fix a missing IAM role, and editing IAM won’t fix a revoked authorization.

Check 1: the account’s roles on the bucket

In the Google Cloud console, open the project that owns the bucket and review the IAM roles for the account you signed in with. As covered in our Windows setup guide for Google Cloud Storage, Storage Object Viewer is enough for read-only access, and Storage Object Admin is needed to write.

Two situations catch people out:

1. The account has a role on the project but not on the specific bucket, or the bucket uses its own access settings.
2. Someone changed the roles after the drive was first set up, so a write that worked last month now fails.

If NetDrive lists no buckets after a successful sign-in, this is the first place to look. For unattended machines, use a dedicated service account so the mount doesn’t depend on one person’s login.

Check 2: the Google account’s own state

A password change, a forced sign-out after a suspicious-login flag, or a review of connected apps can invalidate an existing authorization. Sign in to the Google account in a browser and look at the third-party access settings. If NetDrive’s entry is gone, access was revoked, and reconnecting is the fix.

Reconnect the drive in NetDrive

Reconnecting replaces the stored credentials with a fresh authorization. The mount point and other drive settings stay as they are.

1. Open NetDrive and find the Google Cloud Storage drive in Drive Manager.
2. Open the drive’s settings and choose to re-authenticate or reconnect.
3. Complete the Google sign-in in your browser and approve access.
4. Click Test to confirm NetDrive can reach the bucket.
5. Mount the drive again from Drive Manager.

If that doesn’t clear the error, remove the drive from Drive Manager and add it again. That forces a brand-new authorization instead of refreshing a broken one.

When authentication is not the problem

If Test passes but files look wrong afterward, the cause has moved past sign-in. A folder listing that seems out of date responds to a manual refresh; see Force Folder Refresh in NetDrive. If the failure only appears on write, go back to the IAM roles above.

Wrap-up

Most GCS authentication errors in NetDrive come from Google, not NetDrive: a role that doesn’t cover the bucket, or an authorization Google no longer honors. Work out which symptom you have, check the roles, confirm the account state, then reconnect through Drive Manager. For similar sign-in fixes on other providers, see Fix Azure File Storage Authentication Errors and Fix Backblaze B2 Authentication Errors.

— Kai, NetDrive