What
When Claude Code talks to Claude through Google Cloud (with CLAUDE_CODE_USE_VERTEX or CLAUDE_CODE_USE_ANTHROPIC_GOOGLE_CLOUD set), it recognises more errors as credential problems and reports them as "Google Cloud" credential issues. Before, it recognised only a few messages such as "Could not load the default credentials" and "invalid_grant". It now also recognises:
- A key file that is missing ("does not exist, or it is not a file").
- A key file whose contents are not valid credentials.
- A key file that is not valid JSON, the text format credentials are stored in.
- A key file Claude Code is not permitted to open or read.
Why
If your Google Cloud key file is missing, broken or unreadable, you now get an error that points at your credentials instead of a generic failure, so it is clearer what to fix.
Names in the bundleCLAUDE_CODE_USE_VERTEXCLAUDE_CODE_USE_ANTHROPIC_GOOGLE_CLOUD
Documented inclaude-code/agent-sdk/quickstart
The entry above is what we published on the day. These lines were added later, as Anthropic's own pages caught up, and they sit beside the original rather than replacing it.
Added since
A small documentation edit on Connect Claude Code to an LLM gateway touched a line naming CLAUDE_CODE_USE_VERTEX after this was published.
| `400` errors naming `thinking` or `adaptive`, such as `Input tag 'adaptive' found` | The upstream model build doesn't accept adaptive reasoning, which Claude Code requests for Claude Opus 4.6, Claude Sonnet 4.6, Claude Haiku 5.5, Claude …llm-gateway-connect see the edit
Confirmed since
Anthropic's documentation has since written up CLAUDE_CODE_USE_VERTEX, on Customize sessions in self-hosted environments.
export CLAUDE_CODE_USE_VERTEX=1self-hosted-environments-configuration see the edit
One source agreesOne thing we can check says the same as this entry.
Anthropic's documentation agrees
Anthropic's documentation has since written up CLAUDE_CODE_USE_VERTEX, on Customize sessions in self-hosted environments.