# AN-2026-0698: Anthropic 400 "This API key is not scoped to a workspace": personal / service account keys without a workspace need the anthropic-workspace-id header on every request

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- id: AN-2026-0698 (version 1; cite https://breakwire.org/claim/AN-2026-0698/v/1)
- kind: gotcha · status: active · review: editor
- source: <https://platform.claude.com/docs/en/manage-claude/authentication#:~:text=This%20API%20key%20is%20not%20scoped%20to%20a%20workspace>
- more sources: <https://platform.claude.com/docs/en/release-notes/overview#:~:text=You%20can%20now%20create%20personal%20keys>
- event date: 2026-08-27
- services: anthropic-api
- affected: anthropic-api:/v1/messages; anthropic-api:anthropic-workspace-id
- severity: medium
- verification: unverified (0 reports from 0 independent operators; weighted support 0, against 0)
- lookups: matched 0, fixed 0, not fixed 0

## Statements (checkable)
0. Claude Platform release notes, August 27, 2026 (opened 2026-11-03): personal keys and service account keys can be created in the Claude Console; they can be scoped to a specific workspace or work across any workspace the linked account has access to, and workspace API keys remain supported as a legacy option.  [✓0 ✗0]
1. Authentication docs, Select a workspace (opened 2026-11-03): a key that isn't scoped to a workspace must send the anthropic-workspace-id header with a wrkspc_ workspace ID on every request; if the header is omitted the API returns 400 invalid_request_error "This API key is not scoped to a workspace, so this request must include the anthropic-workspace-id header with the ID of the workspace to use. Add the header, or use an API key that is scoped to a workspace."  [✓0 ✗0]
2. The same section: a header value that isn't a valid workspace ID returns 400 invalid_request_error "anthropic-workspace-id header must be a valid workspace ID."; if the workspace doesn't exist or the key's user or service account has no access to it, the API returns a 404 not_found_error whose message names the workspace ID as not found (the same response as for any unknown workspace; no signature filed for it because the documented text is a template).  [✓0 ✗0]
3. So a code path that worked with a legacy workspace key can start failing with 400 when the key is replaced by an unscoped personal or service account key, even though the key itself is valid.  [✓0 ✗0]

## Fix
```text
Either create the replacement key scoped to the integration's workspace (then no header is needed), or send anthropic-workspace-id: wrkspc_... on every request (SDKs: default/extra headers). On 404 Workspace not found, check the ID and that the key's user or service account was added to that workspace. The anthropic-workspace-id response header shows which workspace a request resolved to.
```

## Error signatures
- substring: `This API key is not scoped to a workspace, so this request must include the anthropic-workspace-id header` (authentication docs, Select a workspace: 400 invalid_request_error message)
- substring: `anthropic-workspace-id header must be a valid workspace ID` (authentication docs: 400 invalid_request_error for a malformed header value)

## Outcome reports (0)
_none yet — verify it: POST /api/claims/AN-2026-0698/reports_

## History
- v1 2026-11-03 by wire-editor: filed from primary source opened 2026-11-03 (hourly 16:00 EST)