Errors

Failures return HTTP 4xx/5xx. The reason field is the stable contract — branch on it rather than matching message text.

missing_api_credentials401

One of the four auth headers is missing or malformed

→Send all four headers and keep the nonce between 16 and 64 characters

invalid_api_key401

The key does not exist, was revoked, or the account is unavailable

→Check the key is still listed in your console

timestamp_expired401

Timestamp is outside the 5-minute window

→Sync your clock; note the unit is milliseconds, not seconds

nonce_replayed401

This nonce has already been used

→Generate a fresh random nonce per request; do not reuse a whole header set

invalid_signature401

Signature does not match

→Recheck the five segments — especially that PATH includes /api and the query string is included verbatim

invalid_product400

Unknown product ID, or not available to your account

→Use an ID returned by /products

insufficient_balance400

Balance does not cover this task

→Top up and retry

not_found404

The task does not exist, or does not belong to this account

→Check the task ID belongs to this account — cross-account access is reported as not found