Empty and tiny images
2026-01-28 · Captchas
A zero-byte body and a picture with no letters both come back as an image error, and you are not charged.
An empty file has nothing to decode. You get error: invalid_image and charged is false. The same happens for a file that is not one of the accepted formats.
A tiny crop that missed the letters fails the same way, or it returns an unreliable short string. Check the crop before you call the API. The captcha element on the page is the right rectangle.
The task-style API uses different names for the same ideas. An empty file is ERROR_ZERO_CAPTCHA_FILESIZE. An undecodable file is ERROR_IMAGE_TYPE_NOT_SUPPORTED. A low-confidence read is ERROR_CAPTCHA_UNSOLVABLE, and it is not charged.
Either API is enough. Use the task routes only when an existing client already speaks them.
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