Documentation

Error reference

Every JSON error response has the same shape: { ok: false, error: <code>, message: <human-readable text> }. The error code is stable and meant to be matched on in code; the message is meant to be read by a person and can change wording.

Ingest endpoint

Errors from posting a submission to send.webforms.to.

Code	HTTP	Where	Meaning
`missing_access_key`	400	Ingest	No key in the URL path or an access_key field in the body.
`form_not_found`	404	Ingest	The key doesn't match any form, or the form is deactivated.
`method_not_allowed`	405	Ingest	Something other than POST (or the OPTIONS preflight).
`rate_limited`	429	Ingest / all APIs	Per-IP or per-key burst limit hit. Check retry-after / X-RateLimit-Reset.
`account_unverified`	403	Ingest	No owner/admin on the workspace has a verified, unblocked account, so the form is inactive.
`quota_exceeded`	402	Ingest	The workspace's monthly submission limit has been reached.
`validation_failed`	422	Ingest	The submission didn't match the form's field schema. issues lists each failing field.

Submissions API / write API / MCP

Cross-cutting errors that any authenticated endpoint can return.

Code	HTTP	Where	Meaning
`unauthorized`	401	Submissions API / write API / MCP	Missing, malformed or revoked API key. Identical body whether the key never existed or was revoked, so the endpoint can't be used to enumerate valid keys.
`insufficient_scope`	403	Write API	The key doesn't carry the scope the endpoint requires - forms:write, destinations:write, routes:write, templates:write, api_keys:write or members:write.
`plan_required`	403	Write API	The workspace's plan doesn't include the feature being configured (routing rules, custom templates, domain allowlist, autoresponder, custom thank-you page).
`not_found`	404	Submissions API / write API	No such resource in this workspace - including when the id is real but belongs to a different workspace. Never distinguishes the two.
`invalid_cursor`	400	Submissions API	The cursor query parameter isn't one this API issued.
`invalid_status`	400	Submissions API	An unrecognised value in the status filter.

Write API specifics

Errors specific to individual write endpoints.

Code	HTTP	Where	Meaning
`invalid_name`	400	Forms, templates	Empty or over the length limit.
`invalid_input`	400	Destinations, Forms	A field failed validation - malformed webhook URL, SSRF-blocked host, invalid Slack/Discord/Telegram config, or an invalid customJsonSuccess/customJsonError key or value on a form's confirmation settings.
`invalid_provider`	400	Destinations	Not one of email, slack, discord, telegram, webhook.
`unverified_address`	400	Destinations	An email destination must point at a verified linked address for the workspace.
`linked_email_limit`	403	Destinations	The plan's ceiling on distinct linked email addresses would be exceeded.
`unsupported`	400	Destinations	The destination's provider can't be edited through this endpoint.
`invalid_route`	400	Routes	The condition tree is malformed - see the routing rules validation rules.
`invalid_conditions`	400	Routes	A new rule was posted with no conditions. Only the default rule may have none, and it already exists.
`invalid_destination`	400	Routes	One of the integrationIds doesn't belong to this workspace.
`invalid_direction`	400	Routes	Reorder direction must be "up" or "down".
`cannot_delete_default`	400	Routes	The default (catch-all) rule can't be deleted.
`cannot_disable_default`	400	Routes	The default rule can't be paused.
`invalid_template`	400	Forms, templates	Unknown built-in template id, or a custom template id that doesn't parse.
`invalid_subject`	400	Templates	Empty or over the length limit.
`invalid_html`	400	Templates	Empty or over the size limit.
`template_limit`	403	Templates	The plan's ceiling on saved custom templates would be exceeded.
`cannot_change_owner`	400	Members	The workspace owner's role can't be changed through this endpoint.
`cannot_remove_owner`	400	Members	The workspace owner can't be removed.
`invalid_slug`	400	Workspace	Under 3 characters after normalizing to lowercase letters, numbers and hyphens.
`slug_taken`	400	Workspace	Another workspace already uses that slug.

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