paypal express checkout =>Error: Security header is not valid

Question

Error : Security header is not valid Array

(
    [TIMESTAMP] => 2014%2d04%2d29T07%3a24%3a29Z
    [CORRELATIONID] => 6af6749c848d6
    [ACK] => Failu         


        

Answer 1

It doesn't always mean invalid API credential or wrong endpoint

If you're absolutely sure in this info, check the encoding you're making your request with - it should be UTF-8 without Byte-Order Mark (BOM), e.g (in Visual C# .NET)

var requestEncoding = new UTF8Encoding(false); // UTF-8 without BOM

using (var streamWriter = new StreamWriter(request.GetRequestStream(), requestEncoding))
{
    streamWriter.Write(requestBody);
}

This is not a default value, and it helped me after an hour of checking everything

Of course, make sure all of your parameters are URL encoded, too