PayPal REST API .net SDK - 400 Bad Requests

Question

I'm working in the sandbox and using the PayPal REST .net SDK method Payment.Create with a CreditCard object. When all parameters are valid and using the test CC number from https://developer.paypal.com/webapps/developer/docs/integration/direct/accept-credit-cards/, the Payment object is returned from that method and all is well.

However, when a parameter is not valid, such as a past expiration date or a CC number not recognized by the sandbox, the Payment object is not returned. Instead the method throws an exception: "Exception in HttpConnection Execute: Invalid HTTP response The remote server returned an error: (400) Bad Request", but with no further explanation.

When I execute the same request in cURL, in addition to the "400 Bad Request", I get a JSON response. This includes more helpful messages such as "VALIDATION_ERROR" and "Invalid expiration (cannot be in the past)".

My question: Is there a way to get these messages back from the SDK?

What I've tried:

• PayPal docs: https://developer.paypal.com/webapps/developer/docs/api/#errors This document mentions that in the case of an error, they return the details in the body of the response. Unfortunately, it doesn't give a clue about whether these are accessible by the SDK.
• Various Google and SO searches.
• The PizzaApp sample code provided with the SDK has nothing in the way of exception handling or further insight into this problem.
• I see a PayPalException object in the SDK, but have not found anything that indicates how it should be used or if it's even relevant to this problem.

All help is much appreciated.

Answer 1

I only started messing with the SDK and API today and ran into this issue right away. I mean, if I'm going to create my own form to handle payments, I'd like to give my user's feedback if anything went wrong.

In any case, I did find some hidden info in the inner exception. Maybe this will help.

catch (PayPal.Exception.PayPalException ex)
{
    if (ex.InnerException is PayPal.Exception.ConnectionException)
    {
        context.Response.Write(((PayPal.Exception.ConnectionException)ex.InnerException).Response);
    }
    else
    {
        context.Response.Write(ex.Message);
    }
}

The resulting response:

{"name":"VALIDATION_ERROR","details":[{"field":"payer.funding_instruments[0].credit_card.number","issue":"Must be numeric"}],"message":"Invalid request - see details","information_link":"https://developer.paypal.com/webapps/developer/docs/api/#VALIDATION_ERROR","debug_id":"0548e52ef9d95"} 

Answer 2

Since no one seems to know the answer to this, I dug into the source code of PayPal's .NET SDK for REST API. From this review, it appears that as of the current version, there is no provision for returning the error messages when any 4xx or 5xx HTTP status code is returned by the server. I referenced the answers to this question and have altered the SDK to allow for returning the error response when applicable. Here's the relevant portion of HttpConnection.cs.

catch (WebException ex)
{
    if (ex.Response is HttpWebResponse)
    {
        HttpStatusCode statusCode = ((HttpWebResponse)ex.Response).StatusCode;
        logger.Info("Got " + statusCode.ToString() + " response from server");
        using (WebResponse wResponse = (HttpWebResponse)ex.Response)
        {
            using (Stream data = wResponse.GetResponseStream ())
            {
                string text = new StreamReader (data).ReadToEnd ();
                return text;
            }
        }                           
    }
    if (!RequiresRetry(ex))
    {
        // Server responses in the range of 4xx and 5xx throw a WebException
        throw new ConnectionException("Invalid HTTP response " + ex.Message);
    }                       
}

Of course, this requires changes to the calling function to properly interpret the error response. Since I'm only using the Payment Create API, I took some shortcuts that wouldn't work for general use. However, the basic idea is that I created PaymentError and Detail classes, then altered the Payment.Create and PayPalResource.ConfigureAndExecute methods to populate and pass back a PaymentError object.

---

Three years later and there is some improvement in PayPal's API error response handling. Because of some other issues I had to re-work my application, and rip out the prior code. I've found that you can now trap for a PayPal.Exception.PaymentsException, then deserialize the JSON Response string into a PayPal.Exception.PaymentsError object.

Catch ex As PayPal.Exception.PaymentsException
    Dim tmpPmtErr As PayPal.Exception.PaymentsError = _
        JsonConvert.DeserializeObject(Of PayPal.Exception.PaymentsError)(ex.Response)

Thanks to @lance in the other answer for the heads-up to examine the exceptions more closely. I attempted to use that solution, but could not make it work.

Answer 3

This seems to have changed, and while many of these answers point in the right direction, none of them worked exactly for me. This is my equivalent of the currently most upvoted answer:

catch (PayPal.PaymentsException ex)
{
    context.Response.Write(ex.Response);
}

with the response:

{"name":"VALIDATION_ERROR","details":[{"field":"start_date","issue":"Agreement start date is required, should be valid and greater than the current date. Should be consistent with ISO 8601 Format"}],"message":"Invalid request. See details.","information_link":"https://developer.paypal.com/docs/api/payments.billing-agreements#errors","debug_id":"8c56c13fccd49"}

Answer 4

@Jonathan, The REST API has log4net integrated and will output the full error response to a log file if you set it up. You must add this config section to your web.config:

<section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler, log4net"/>

and also set the options:

<log4net>
<appender name="FileAppender" type="log4net.Appender.FileAppender">
  <file value="rest-api.log"/>
  <appendToFile value="true"/>
  <layout type="log4net.Layout.PatternLayout">
    <conversionPattern value="%date [%thread] %-5level %logger [%property{NDC}] %message%newline"/>
  </layout>
</appender>
<root>
  <level value="DEBUG"/>
  <appender-ref ref="FileAppender"/>
</root>

Open your global.asax and add this into the Application_Start:

log4net.Config.XmlConfigurator.Configure();

Now, as long as there are write permissions set on your log folder, then the PayPal REST SDK will spit out error messages to the log file.

Answer 5

My problem was that my total, detail.subtotal, and items.price were passing in values like $1,000.00 and it needs decimal so use something like:

total = Regex.Replace(model.OrderTotal, "[^0-9.]", "")

Answer 6

Improving the solution here is... Simply (Imports PayPal)

    Try
    Catch ex As PaymentsException
        For Each i In ex.Details.details
            Response.Write(i.field) 'Name of Field
            Response.Write(i.code) 'Code If Any
            Response.Write(i.issue) 'Validation Issue
        Next
    End Try

Answer 7

All of the above solution of dont really grasp the problem ..

I ran in to a similar problem a while back .. after debugging my code i found out that the transaction that i was making was logically wrong.. the subtotal was off be $0.25 and paypal server saw it and refused to process it, and gave me 400 bad request

Answer 8

If you are using a globalization outside the US you need to convert your decimals to a InvariantCulture:

order.GetTotal().ToString("N2", CultureInfo.InvariantCulture)