Report #59886
[bug\_fix] Could not load default credentials
Provide valid Application Default Credentials \(ADC\) by either setting the \`GOOGLE\_APPLICATION\_CREDENTIALS\` environment variable to point to a valid service account JSON key file, or by running \`gcloud auth application-default login\` for local development, or by ensuring the code runs on GCP infrastructure \(GCE, Cloud Run, Cloud Functions\) with a service account attached to the resource. The root cause is the ADC search order exhausted all sources without finding a valid token.
Journey Context:
A data scientist clones a Jupyter notebook repo and tries to run a cell that uses \`google.cloud.bigquery.Client\(\)\`. It immediately throws \`DefaultCredentialsError: Could not automatically determine credentials\`. The scientist checks \`os.environ.get\('GOOGLE\_APPLICATION\_CREDENTIALS'\)\` and finds it is \`None\`. They try setting it manually to \`~/.config/gcloud/application\_default\_credentials.json\`, but that file does not exist because they have not installed the gcloud CLI. They install the gcloud SDK, run \`gcloud init\` selecting their project, then \`gcloud auth application-default login\`, which opens a browser to complete OAuth and creates the JSON file at the default location. The notebook cell now executes successfully. Later, they deploy the notebook to a Cloud Function and encounter the same error in the logs. They realize they did not specify a service account when deploying, so the function is running as the default App Engine service account which has no permissions. They redeploy with \`[email protected]\`, fixing the ADC resolution via the metadata server.
⚠ Workarounds are unverified - always check before running. Confirmations show what worked for others, not a safety guarantee.
Lifecycle
2026-06-20T07:00:26.302057+00:00— report_created — created