While pushing expenses to Great Plains, you may get an error like below 

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Timestamp:5/16/2014 11:05:56 AM Category:GP Exception Priority:1  EventId:102 Severity:Critical
                  Title:Exception while processing Expense Record GE101-0
           Message:Exception while processing Expense Record GE101-0 Transaction Count - 1Amount - 200.0000 Credit Entity - Cash Currency USDFirst ERP Account ID ---61100-001-0000-00000-016 Exception Message - System.Net.WebException: The request failed with HTTP status 404: Not Found.
   at System.Web.Services.Protocols.SoapHttpClientProtocol.ReadResponse(SoapClientMessage message, WebResponse response, Stream responseStream, Boolean asyncCall)
   at System.Web.Services.Protocols.SoapHttpClientProtocol.Invoke(String methodName, Object[] parameters)
   at GorillExpense.IntegrationApp.DynamicsGPService2013Legacy.DynamicsGP.GetPolicyByOperation(String operation, Context context)
   at GorillExpense.IntegrationApp.Classes.GP2013PayablesInvoiceUpload.GPProcessSingleBatch(List`1 exp, List`1 memoFlds, Decimal total_amt)
                  
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Timestamp:5/16/2014 11:05:56 AM Category:Main GP Exception Priority:1  EventId:100 Severity:Critical
                  Title:Exception while processing GP Upload 
           Message:GPPayablesInvoiceUpload.cs System.Net.WebException: The request failed with HTTP status 404: Not Found.
   at System.Web.Services.Protocols.SoapHttpClientProtocol.ReadResponse(SoapClientMessage message, WebResponse response, Stream responseStream, Boolean asyncCall)
   at System.Web.Services.Protocols.SoapHttpClientProtocol.Invoke(String methodName, Object[] parameters)
   at GorillExpense.IntegrationApp.DynamicsGPService2013Legacy.DynamicsGP.GetPolicyByOperation(String operation, Context context)
   at GorillExpense.IntegrationApp.Classes.GP2013PayablesInvoiceUpload.GPProcessSingleBatch(List`1 exp, List`1 memoFlds, Decimal total_amt)
   at GorillExpense.IntegrationApp.Classes.GP2013PayablesInvoiceUpload.GPProcessSingleExpense(List`1 ListExpenseInfo, List`1 Listsettings, List`1 ListConfigLabelInfo)
                  
-------------------------------
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Timestamp:5/16/2014 11:05:56 AM Category:Update UnSuccessful Priority:1  EventId:1 Severity:Information
                  Title:Failed
           Message:ExpesnseId = 101 ExpesnseNo = GE101

To resolve the issue, please make sure your URL on the settings page of the Integration app is in the following format if connecting to GP-

http://machinename:port/DynamicsGPWebServices/DynamicsGPService.asmx


For NAV, you may get  a similar error as well, if your URL is not entered properly. Please copy the URL from the settings page of the integration app and open it in the browser to ensure it loads.