Code 0 is for "no errors".
Account authorization key not found in the system. Make sure you copied it correctly without spaces and tabulation signs.
No idle captcha workers are available at the moment
Account has zero or negative balance.
Captcha could not be solved, see errorDescription field
Captcha you are requesting does not exist in your active captchas list or has been expired
Task type is not supported or typed incorrectly. Please check "type" property in task object
System suspended your account for a significant reason. Contact support for details.
See errorDescription property for more details