> ## Documentation Index > Fetch the complete documentation index at: https://api-doc.fidly.be/llms.txt > Use this file to discover all available pages before exploring further. # Errors > One envelope for every error, with a machine-readable code, grouped by resource. Every error uses the same envelope, in English: ```json theme={null} { "error": { "code": "invalid_filter", "message": "Invalid type 'x'. Allowed: [...]" } } ``` `code` is stable and snake\_case — branch on it, not on the message. `message` is human-readable and safe to log. No stack trace is ever returned. ## General Body or parameter failing schema validation; message is `field: reason`. Unknown value in a list filter (also unknown `language` on reference lists, unknown `format` on file download). Query parameter that does not apply to the targeted resource (e.g. `?ignore_duplicate` on a contact). Read-only field in a `PATCH` — `bic`/`reference` of a non-manual bank account, `code`/`category`/`sequence_scope` of a journal, `type`/`journal_id` of a document — or a field that does not exist for the relation's type. Unknown route or unknown UUID (including a UUID of another company). Unexpected server error, logged on our side. Retry later; if it persists, contact support with the `X-Request-ID` from the response header — it lets us pull that request's trace straight away and speeds up handling (see [Conventions](/en/conventions#tracing-a-request)). ## Authentication Missing credential field on `/auth/token`. Unknown `client_id` or wrong `client_secret`. Unknown, already-used or revoked `refresh_token`. The client has been deactivated. Missing, malformed or expired `access_token`. The `access_token` lacks the required permission. Too many failed authentications on this `client_id`. ## Documents `relation_id` unknown, belonging to another company, or with no address. Journal unknown, inactive, of another company, or of the wrong category for the document type. No `journal_id` given and the company has no default journal for the category. Delivery location unknown or belonging to another relation than the document's. Document total negative. Declared `paid_amount` above the document total. Document-level discount/charge on lines totalling 0, or a VAT rate whose lines total a negative amount. Date outside the bracket of the neighbouring numbered documents, or outside the numbering window. Stored lines that cannot be reused for a recompute — send the full `lines` array instead. Creating a purchase document while self-billing is not enabled for the company. Sending a document type Peppol does not transport (e.g. a proforma). As a `409`: sending a **received** document. The send workflow could not be started. With `?send_peppol=true` the document **was** created — the message gives its id; recover with `POST /documents/{id}/send`, never a second creation. Peppol send on a document already sent — only a failed send (`peppol_status` `failed` or `rejected`) can be retried. Attachment filename already present on the document. `PATCH` on a document already sent to the customer, already transmitted to accounting, or received. `DELETE` on a document that is not the last of its sequence, already sent, transmitted, or received. `DELETE` on a document linked to a reconciliation, an invoiced timesheet line or a payment intent. Import and attachments also return plain HTTP statuses: `413` (file too big) and `415` (extension not allowed). ## Relations Company whose `vat`, `identifier` or `electronic_address` already exists — bypass with `?ignore_duplicate=true`; the message gives the existing id. Address without `country_code`, or `street_number` without `street`. `DELETE` on a relation still referenced (document, subscription, project, timesheet line, accounting match...). The message says what blocks. ## Delivery locations Address without `country_code`, or `street_number` without `street` — the same rules as a relation's address. `identifier` / `identifier_scheme` pair half-filled. On a document: location unknown or belonging to another relation than the document's. `DELETE` on a delivery location a document is delivered to. ## Bank accounts Account with the same `reference` (IBAN) already exists. Demoting the default bank account without promoting another. ## Journals Journal `code` already used in the company. Default journal created or left inactive, or demoting the last default of a category. `bank_account_id` matching no account of the company. ## Brandings Demoting the default branding — promote another instead.