These errors may happen for every operation. Some of them are related to authentication and some are related to the operation.
<Error> <Code>-21</Code> <Message>authentication header is not available</Message> </Error>
<Error> <Code>-22</Code> <Message>authentication header is damaged</Message> </Error>
<Error> <Code>-23</Code> <Message>username or password is not present in the authentication header</Message> </Error>
<Error> <Code>-24</Code> <Message>username or password is wrong</Message> </Error>
<Error> <Code>-31</Code> <Message>requested url is not valid</Message> </Error>
<Error> <Code>-32</Code> <Message>requested operation is not a valid operation</Message> </Error>
<Error> <Code>-33</Code> <Message>requested operation has invalid arguments</Message> </Error>