On the wire
Ships with HTTP status 400, carrying "code": "RU-3011" in the response body alongside the human-readable error message. Existing fields are never replaced by the code: it is additive.
Common causes
- Selecting a Growth- or Scale-only region (e.g. London, Singapore, Sydney, Toronto, Chicago, São Paulo) on Free.
- Selecting a Scale-only region (Toronto or São Paulo) on Growth.
- An account that downgraded and still has an out-of-plan region selected on an existing check (existing checks are not truncated -- see updateCheckRegions' doc comment -- but cannot be RE-saved with the same out-of-plan region).
How to fix it
- Select a region included in your current plan (see /pricing for the per-tier region list).
- Upgrade to a plan that includes the region you need.
Related codes
Still stuck?
Ask support and mention RU-3011: the code pins down the exact refusal path, so you skip the diagnostic back-and-forth.