Paypal Error when returning from payment

[egormsen]

Our customers are getting an error when they pay using paypal - they are getting to paypal and the payment is made, but when they try to return to the store by clicking on the return to store ink in paypal they get an error. The orders are getting completed and the payment is processing fine, but it looks bad and is confusing for people when they get the error.

Anyone else seen this problem or know of a resolution?

Here are the details of the error from event viewer on the websever.

Event code: 3005
Event message: An unhandled exception has occurred.
Event time: 6/30/2011 8:58:51 AM
Event time (UTC): 6/30/2011 1:58:51 PM
Event ID: d3ca80840b2f4dfebfb24e8892740673
Event sequence: 24323
Event occurrence: 3
Event detail code: 0

Application information:
Application domain: /LM/W3SVC/4/ROOT-4-129538611972717500
Trust level: Full
Application Virtual Path: /
Application Path: C:\XXXXXX\wwwroot\MYSTORE\
Machine name: STOREWEB

Process information:
Process ID: 4476
Process name: w3wp.exe
Account name: NT AUTHORITY\NETWORK SERVICE

Exception information:
Exception type: WebException
Exception message: The remote server returned an error: (400) Bad Request.

Request information:
Request URL: https://mystore.mystore.com:443/Process ... erId=37367
Request path: /ProcessPayPal.ashx
User host address: XXX.XXX.XXX.XXX
User: user@user.com
Is authenticated: True
Authentication Type: Forms
Thread account name: NT AUTHORITY\NETWORK SERVICE

Thread information:
Thread ID: 11
Thread account name: NT AUTHORITY\NETWORK SERVICE
Is impersonating: False
Stack trace: at System.Net.HttpWebRequest.GetResponse()
at CommerceBuilder.Payments.Providers.PayPal.PayPalProvider.ValidateNotification(String formValues)
at CommerceBuilder.Payments.Providers.PayPal.IpnProcessor.ProcessRequest(HttpContext context)
at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)

Here are the details of our AC installation:
: 7.0.7.14481
MSSQL v2008
AC SCHEMA v2005
.NET CLR v2.0.50727.4211
ASP.NET TRUST: Unrestricted

AbleMods.QBClasses: 1.5.1.0
AbleMods.QBWebService: 1.5.0.0
AjaxControlToolkit: 3.0.20229.20843
App_Licenses: 0.0.0.0
BasicFrame.WebControls.BasicDatePicker: 1.4.0.25598
CommerceBuilder: 7.7.14421.0
CommerceBuilder.AbleCommerceTax: 7.4.13043.0
CommerceBuilder.AcTestProvider: 1.0.0.0
CommerceBuilder.AustraliaPost: 7.1.0.0
CommerceBuilder.AuthorizeNet: 7.3.12625.0
CommerceBuilder.AvaTax: 7.6.14440.0
CommerceBuilder.BankOfCanada: 7.3.0.0
CommerceBuilder.CanadaPost: 7.0.0.0
CommerceBuilder.Configuration: 7.7.14421.0
CommerceBuilder.CyberSource: 7.5.13718.0
CommerceBuilder.Data: 7.7.14421.0
CommerceBuilder.DataClient.Api: 7.7.14430.0
CommerceBuilder.DataClient.Csv: 1.0.0.0
CommerceBuilder.DHLInternational: 7.2.11307.0
CommerceBuilder.ECB: 7.0.0.0
CommerceBuilder.FedEx: 7.0.9725.0
CommerceBuilder.FedExWS: 7.0.9725.0
CommerceBuilder.GoogleCheckout: 7.6.14238.0
CommerceBuilder.InternetSecure: 7.0.9764.0
CommerceBuilder.LinkPoint: 7.0.9764.0
CommerceBuilder.Paradata: 7.0.9764.0
CommerceBuilder.PayFlowPro: 7.0.10061.0
CommerceBuilder.PayJunction: 7.3.12625.0
CommerceBuilder.PaymentechOrbital: 7.4.14341.0
CommerceBuilder.PayPal: 7.6.14103.0
CommerceBuilder.Protx: 7.3.12327.0
CommerceBuilder.Services: 7.7.14421.0
CommerceBuilder.SkipJack: 7.1.14438.0
CommerceBuilder.UPS: 7.0.10041.0
CommerceBuilder.USPS: 7.3.14358.0
CommerceBuilder.WATax: 7.5.13942.0
CommerceBuilder.Web: 7.7.14421.0
ComponentArt.Web.UI: 2010.1.2637.35
CS.Web.UI.CropImage: 4.1.5.0
CuteChat: 5.0.0.0
CuteChat.AppCode: 5.0.0.0
CuteWebUI.AjaxUploader: 3.0.0.0
CyberSource.Base: 2.0.0.0
CyberSource.Clients: 5.0.2.0
CyberSource.Clients.XmlSerializers: 5.0.2.0
CyberSource.WSSecurity: 2.0.0.0
CybsWSSecurityIOP: 1.0.0.0
DataPort.Framework: 7.4.221.0
DotNetGallery: 3.1.0.0
FredCK.FCKeditorV2: 2.5.2912.21007
ICSharpCode.SharpZipLib: 0.85.5.452
LinkPointTransaction: 1.0.1797.29766
log4net: 1.2.10.0
NVelocity: 7.2.0.0
PaygatewayNET: 3.0.0.0
paypal_base: 4.2.1.0
PFProCOMLib: 1.0.0.0
PFProdotNET: 0.0.0.0
StructuredSolutions.ShippingAgent: 3.0.3215.22405
StructuredSolutions.ShippingAgent.AbleCommerce7: 3.0.3215.22413
TimePicker: 1.0.0.0
Validators: 1.0.0.0
WebChart: 1.1.1.6
wwHoverPanel: 1.85.0.0

[WebDev7]

Check in your actual PayPal account. You may not have the "auto return" set to ON and the correct URL entered from AbleCommerce PayPal Gateway entered.

Let me know how this works for you.