gsutil copy returning "AccessDeniedException: 403 Insufficient Permission" from GCE

One other thing to look for is to make sure you set up the appropriate scopes when creating the GCE VM. Even if a VM has a service account attached, it must be assigned devstorage scopes in order to access GCS.

For example, if you had created your VM with devstorage.read_only scope, trying to write to a bucket would fail, even if your service account has permission to write to the bucket. You would need devstorage.full_control or devstorage.read_write.

See the section on Preparing an instance to use service accounts for details.

Note: the default compute service account has very limited scopes (including having read-only to GCS). This is done because the default service account has Project Editor IAM permissions. If you use any user service account this is not typically a problem since user created service accounts get all scope access by default.

After adding necessary scopes to the VM, gsutil may still be using cached credentials which don't have the new scopes. Delete ~/.gsutil before trying the gsutil commands again. (Thanks to @mndrix for pointing this out in the comments.)

You have to log in with an account that has the permissions you need for that project:

gcloud auth login

gsutil config -b

Then surf to the URL it provides, [ CLICK Allow ]

Then copy the verification code and paste to terminal.