Recently upgraded from SQL\SSRS 2008 R2 to SQL\SSRS 2012 SP2 CU4 on our main SSRS server.  We have one report that has a couple subreports and runs/displays correctly when run manually.  When the report runs via a subscription and performs the export to PDF and Excel the subreports do not show and the file has an error message in the bottom of the output "Error: Subreport could not be shown."  The SSRS logs have the following in them when the report runs via subscription:

library!ReportServer_0-8!1700!07/21/2015-06:43:40:: i INFO: Call to GetPermissionsAction(/).
library!ReportServer_0-8!1890!07/21/2015-06:43:40:: i INFO: Call to GetPropertiesAction(/, PathBased).
library!ReportServer_0-8!1700!07/21/2015-06:43:40:: i INFO: Call to GetPropertiesAction(/, PathBased).
library!ReportServer_0-8!1700!07/21/2015-06:43:40:: i INFO: Call to GetSystemPermissionsAction().
library!ReportServer_0-8!1890!07/21/2015-06:43:40:: i INFO: Call to ListChildrenAction(/, False).
library!ReportServer_0-8!ae0!07/21/2015-06:43:40:: i INFO: Call to GetSystemPropertiesAction().
library!ReportServer_0-8!1890!07/21/2015-06:43:40:: i INFO: Call to GetSystemPropertiesAction().
library!ReportServer_0-8!1700!07/21/2015-06:43:40:: i INFO: Call to GetSystemPropertiesAction().
processing!WindowsService_4!1688!07/21/2015-06:43:43:: e ERROR: Throwing Microsoft.ReportingServices.ReportProcessing.ProcessingAbortedException: , Microsoft.ReportingServices.ReportProcessing.ProcessingAbortedException: Report processing has been canceled by the user. ;
processing!WindowsService_4!1688!07/21/2015-06:43:43:: w WARN: Data set 'DailyPADNetRegistrations': Report processing has been aborted.
processing!WindowsService_4!1424!07/21/2015-06:44:54:: e ERROR: Throwing Microsoft.ReportingServices.ReportProcessing.ProcessingAbortedException: , Microsoft.ReportingServices.ReportProcessing.ProcessingAbortedException: Report processing has been canceled by the user. ;
processing!WindowsService_4!1424!07/21/2015-06:44:54:: w WARN: Data set 'DailyPADNetNewStudents': Report processing has been aborted.
library!ReportServer_0-8!1700!07/21/2015-06:45:20:: i INFO: RenderForNewSession('/PADAdminEmbeddedReports/Registrar/Unofficial APUS Transcript')
processing!WindowsService_4!12a4!07/21/2015-06:45:34:: e ERROR: Throwing Microsoft.ReportingServices.ReportProcessing.ProcessingAbortedException: , Microsoft.ReportingServices.ReportProcessing.ProcessingAbortedException: Report processing has been canceled by the user. ;
processing!WindowsService_4!12a4!07/21/2015-06:45:34:: w WARN: Data set 'DailyPADGrossRegistrations': Report processing has been aborted.
library!ReportServer_0-8!1700!07/21/2015-06:46:02:: i INFO: RenderForNewSession('/PADAdminEmbeddedReports/Registrar/Official APUS Transcript')
library!ReportServer_0-8!1424!07/21/2015-06:46:04:: i INFO: RenderForNewSession('/PADAdminEmbeddedReports/Registrar/Official APUS Transcript')
library!ReportServer_0-8!16b4!07/21/2015-06:48:40:: i INFO: Call to GetPermissionsAction(/).
library!ReportServer_0-8!1890!07/21/2015-06:48:40:: i INFO: Call to GetPropertiesAction(/, PathBased).
library!ReportServer_0-8!16b4!07/21/2015-06:48:40:: i INFO: Call to GetPropertiesAction(/, PathBased).
library!ReportServer_0-8!16b4!07/21/2015-06:48:40:: i INFO: Call to GetSystemPermissionsAction().
library!ReportServer_0-8!1890!07/21/2015-06:48:40:: i INFO: Call to ListChildrenAction(/, False).
library!ReportServer_0-8!16b4!07/21/2015-06:48:40:: i INFO: Call to GetSystemPropertiesAction().
library!ReportServer_0-8!16b4!07/21/2015-06:48:40:: i INFO: Call to GetSystemPropertiesAction().
library!ReportServer_0-8!16b4!07/21/2015-06:48:40:: i INFO: Call to GetSystemPropertiesAction().
library!WindowsService_4!1ba8!07/21/2015-06:51:14:: i INFO: Call to CleanBatch()
library!WindowsService_4!1ba8!07/21/2015-06:51:14:: i INFO: Cleaned 0 batch records, 0 policies, 0 sessions, 0 cache entries, 0 snapshots, 0 chunks, 1 running jobs, 0 persisted streams, 0 segments, 0 segment mappings, 0 edit sessions.
library!WindowsService_4!1ba8!07/21/2015-06:51:14:: i INFO: Call to CleanBatch() ends
runningjobs!WindowsService_4!1ba8!07/21/2015-06:51:14:: i INFO: RunningJobContext.IsExpired; found expired request
processing!WindowsService_4!370!07/21/2015-06:51:52:: e ERROR: Throwing Microsoft.ReportingServices.ReportProcessing.ProcessingAbortedException: , Microsoft.ReportingServices.ReportProcessing.ProcessingAbortedException: Report processing has been canceled by the user. ;
processing!WindowsService_4!370!07/21/2015-06:51:52:: w WARN: Data set 'DailyPADNetNewRegistrations': Report processing has been aborted.
processing!WindowsService_4!e44!07/21/2015-06:51:52:: e ERROR: Throwing Microsoft.ReportingServices.ReportProcessing.ProcessingAbortedException: , Microsoft.ReportingServices.ReportProcessing.ProcessingAbortedException: Report processing has been canceled by the user. ;
processing!WindowsService_4!e44!07/21/2015-06:51:52:: w WARN: Data source 'apus_pad': Report processing has been aborted.
processing!WindowsService_4!e44!07/21/2015-06:51:52:: e ERROR: Throwing Microsoft.ReportingServices.ReportProcessing.ProcessingAbortedException: , Microsoft.ReportingServices.ReportProcessing.ProcessingAbortedException: Report processing has been canceled by the user. ;
processing!WindowsService_4!604!07/21/2015-06:51:52:: e ERROR: Throwing Microsoft.ReportingServices.ReportProcessing.ProcessingAbortedException: , Microsoft.ReportingServices.ReportProcessing.ProcessingAbortedException: Report processing has been canceled by the user. ;
processing!WindowsService_4!604!07/21/2015-06:51:52:: w WARN: Data set 'DailyPADNetNewRegistrations': Report processing has been aborted.
processing!WindowsService_4!1678!07/21/2015-06:51:52:: e ERROR: Throwing Microsoft.ReportingServices.ReportProcessing.ProcessingAbortedException: , Microsoft.ReportingServices.ReportProcessing.ProcessingAbortedException: Report processing has been canceled by the user. ;
processing!WindowsService_4!1678!07/21/2015-06:51:52:: w WARN: Data source 'apus_pad': Report processing has been aborted.
processing!WindowsService_4!1678!07/21/2015-06:51:52:: e ERROR: Throwing Microsoft.ReportingServices.ReportProcessing.ProcessingAbortedException: , Microsoft.ReportingServices.ReportProcessing.ProcessingAbortedException: Report processing has been canceled by the user. ;
processing!WindowsService_4!1678!07/21/2015-06:51:52:: e ERROR: Throwing Microsoft.ReportingServices.ReportProcessing.ProcessingAbortedException: , Microsoft.ReportingServices.ReportProcessing.ProcessingAbortedException: Report processing has been canceled by the user. ;
processing!WindowsService_4!e44!07/21/2015-06:51:52:: e ERROR: Throwing Microsoft.ReportingServices.ReportProcessing.ProcessingAbortedException: , Microsoft.ReportingServices.ReportProcessing.ProcessingAbortedException: Report processing has been canceled by the user. ;
processing!WindowsService_4!1678!07/21/2015-06:51:52:: w WARN: Data source 'apus_pad': Report processing has been aborted.
processing!WindowsService_4!1678!07/21/2015-06:51:52:: e ERROR: Throwing Microsoft.ReportingServices.ReportProcessing.ProcessingAbortedException: , Microsoft.ReportingServices.ReportProcessing.ProcessingAbortedException: Report processing has been canceled by the user. ;
processing!WindowsService_4!e44!07/21/2015-06:51:52:: w WARN: Data source 'apus_pad': Report processing has been aborted.
processing!WindowsService_4!e44!07/21/2015-06:51:52:: e ERROR: Throwing Microsoft.ReportingServices.ReportProcessing.ProcessingAbortedException: , Microsoft.ReportingServices.ReportProcessing.ProcessingAbortedException: Report processing has been canceled by the user. ;
library!WindowsService_4!1678!07/21/2015-06:52:11:: i INFO: Initializing EnableRemoteErrors to 'False'  as specified in Server system properties.
reportrendering!WindowsService_4!1678!07/21/2015-06:52:11:: e ERROR: Throwing Microsoft.ReportingServices.ReportProcessing.RenderingObjectModelException: , Microsoft.ReportingServices.ReportProcessing.RenderingObjectModelException: Data retrieval failed for the subreport, 'Subreport1', located at: /IT/DSupport/Metrics_SubReport1. Please check the log files for more information. ;
processing!WindowsService_4!1678!07/21/2015-06:52:11:: e ERROR: An error has occurred while processing a sub-report. Details: Data retrieval failed for the subreport, 'Subreport1', located at: /IT/DSupport/Metrics_SubReport1. Please check the log files for more information.  Stack trace:
   at Microsoft.ReportingServices.OnDemandReportRendering.SubReport.FinalizeErrorMessageAndThrow()
   at Microsoft.ReportingServices.OnDemandReportRendering.SubReport.RetrieveSubreport()
reportrendering!WindowsService_4!1678!07/21/2015-06:52:11:: e ERROR: Throwing Microsoft.ReportingServices.ReportProcessing.RenderingObjectModelException: , Microsoft.ReportingServices.ReportProcessing.RenderingObjectModelException: Data retrieval failed for the subreport, 'Subreport2', located at: /IT/DSupport/Metrics_SubReport2. Please check the log files for more information. ;
processing!WindowsService_4!1678!07/21/2015-06:52:11:: e ERROR: An error has occurred while processing a sub-report. Details: Data retrieval failed for the subreport, 'Subreport2', located at: /IT/DSupport/Metrics_SubReport2. Please check the log files for more information.  Stack trace:
   at Microsoft.ReportingServices.OnDemandReportRendering.SubReport.FinalizeErrorMessageAndThrow()
   at Microsoft.ReportingServices.OnDemandReportRendering.SubReport.RetrieveSubreport()
reportrendering!WindowsService_4!e44!07/21/2015-06:52:14:: e ERROR: Throwing Microsoft.ReportingServices.ReportProcessing.RenderingObjectModelException: , Microsoft.ReportingServices.ReportProcessing.RenderingObjectModelException: Data retrieval failed for the subreport, 'Subreport1', located at: /IT/DSupport/Metrics_SubReport1. Please check the log files for more information. ;
processing!WindowsService_4!e44!07/21/2015-06:52:14:: e ERROR: An error has occurred while processing a sub-report. Details: Data retrieval failed for the subreport, 'Subreport1', located at: /IT/DSupport/Metrics_SubReport1. Please check the log files for more information.  Stack trace:
   at Microsoft.ReportingServices.OnDemandReportRendering.SubReport.FinalizeErrorMessageAndThrow()
   at Microsoft.ReportingServices.OnDemandReportRendering.SubReport.RetrieveSubreport()
reportrendering!WindowsService_4!e44!07/21/2015-06:52:14:: e ERROR: Throwing Microsoft.ReportingServices.ReportProcessing.RenderingObjectModelException: , Microsoft.ReportingServices.ReportProcessing.RenderingObjectModelException: Data retrieval failed for the subreport, 'Subreport2', located at: /IT/DSupport/Metrics_SubReport2. Please check the log files for more information. ;
processing!WindowsService_4!e44!07/21/2015-06:52:14:: e ERROR: An error has occurred while processing a sub-report. Details: Data retrieval failed for the subreport, 'Subreport2', located at: /IT/DSupport/Metrics_SubReport2. Please check the log files for more information.  Stack trace:
   at Microsoft.ReportingServices.OnDemandReportRendering.SubReport.FinalizeErrorMessageAndThrow()
   at Microsoft.ReportingServices.OnDemandReportRendering.SubReport.RetrieveSubreport()
library!WindowsService_4!1678!07/21/2015-06:52:20:: i INFO: Initializing EnableExecutionLogging to 'True'  as specified in Server system properties.
notification!WindowsService_4!1678!07/21/2015-06:52:20:: i INFO: Notification 4f313c92-02dd-4735-a602-8a5c8200b808 completed.  Success: True, Status: The file "DailyMetrics_20150721.xls" has been saved to the "\\domain\public\studentservices\metrics\ssrsexcel" file share., DeliveryExtension: Report Server FileShare, Report: Metrics, Attempt 0
library!WindowsService_4!e44!07/21/2015-06:52:22:: i INFO: Initializing EnableExecutionLogging to 'True'  as specified in Server system properties.
notification!WindowsService_4!e44!07/21/2015-06:52:22:: i INFO: Notification b89a8c5a-23ed-4a76-88d7-e5d5cec57112 completed.  Success: True, Status: The file "DailyMetrics_20150721.pdf" has been saved to the "\\domain\public\studentservices\metrics\ssrspdf" file share., DeliveryExtension: Report Server FileShare, Report: Metrics, Attempt 0

Hi Dawgndad2,

According to your description, when you run the main report and subreport, they can work fine. But when you create a subscription, subreport cant be shown in the output file, right?

In Reporting Services, to create a subscription, the report must use stored credentials or no credentials to retrieve data at run time. We cannot subscribe to a report that is configured to use the impersonated or delegated credentials of the current user to connect to an external data source. The stored credentials can be a Windows account or a database user account.

From the log file message ERROR: An error has occurred while processing a sub-report. Details: Data retrieval failed for the subreport, 'Subreport1' (Subreport2), the issue is caused by that the subreport is not able to access data source and retrieve data during subscription processing.

In your scenario, please navigate to subreports Subreport1 and Subreport2, open Data Sources page, specify an stored credential, then test the connection and run the subreport to make sure it can work fine.

Reference:
Subscriptions and Delivery (Reporting Services)
Store Credentials in a Reporting Services Data Source

If you have any question, please feel free to ask.

Best regards,
Qiuyun Yu