PayPal Error Codes You May Encounter

If you use PayPal just to pay for things online, you’ll probably never run into error codes. However, if you’re a merchant accepting payments through PayPal, you may want to familiarize yourself with the following error codes and their meanings — or at least know that the info in the following table can help explain things if you do encounter an error message.

Error String or Number	Description
10001	Unexpected error
10002	Authentication error
10003	Missing Required Arguments
10004	Invalid Argument
10005	Unsupported feature
10006	Unsupported version
10007	Permission Denied
10009	Server refused request
11001	Invalid argument warning
11002	FYI warning
PA_Long_Error_ACH_Not_Verified	Your ACH is not verified.
PA_Long_Error_Authentication	Your username or password is incorrect.
PA_Long_Error_Authentication_Not_Authorized	You don’t have the correct permission to call the API.
PA_Long_Error_Authentication_Invalid_Token	Your token is invalid.
PA_Long_Error_Counterparty_Locked_Or_Inactive	The account of the other person in the transaction is either locked or inactive.
PA_Long_Error_Currency_Invalid	The payment currency is invalid.
PA_Long_Error_Currency_Not_Supported	The currency of the payment is not supported.
PA_Long_Error_Memo_Invalid	Invalid characters have been entered into the memo field.
PA_Long_Error_Soap_Header_Null	Your SOAP header is null.
PA_Long_Error_Transaction_Could_Not_Load	The transaction could not be loaded.
PA_Long_Error_Transaction_Id_Invalid	The ID of the transaction is invalid.
PA_Long_Error_User_Locked_Or_Inactive	Your account is either locked or inactive.
PA_Long_Error_User_Restricted	Your account is restricted.
PA_Long_Error_Version_Not_Supported	You are trying to make a call to an unsupported version.
PA_Long_Error_Version_Not_Valid	The version is invalid.
PA_Long_Warning_Encryption_Failed	A warning message letting you know the transaction ID may be incorrect.
PA_Long_Warning_Memo_Truncated	The content of the memo was too long and had to be truncated.
PA_Long_Error_WS_Security	The necessary WS security elements were not found.
PA_Long_Error_Security	The security header is invalid.
PA_Long_Error_Invalid_Account_Number	The account number is not valid.

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Source:http://www.dummies.com/how-to/content/paypal-error-codes-you-may-encounter.html