SSRS 2008 to 2014 Migration Excel Export error We are working on migrating our SSRS from SQL Server 2008 to SQL Server 2014.  After brining the reports over I have a set of reports that will execute just fine but when I try to perform a standard export to excel from the 2014 Server I get a message box saying: 


  We found a problem with some content in ACM Consolidated
  Invoie_2014.xlsx. Do you want us to recover as much as we can?
  If you trust the source of this workbook, click yes.


However, I do not receive the same message when exporting to Excel from the 2008 server.  I believe the problem is related to some Numeric fields that are coming back with a value of 0.0000000000000000000.  Has something changed with the excel export function between these two versions?
This appears to be related to some implicit conversions that are occurring in the background when exporting the report to xlsx.  Numeric columns are being sent to excel as if they are text columns.  One report responded to a change to the query using an Explicit cast to Numeric (Cast as opposed to convert to remove any commas or other formatting that might confuse the conversion).  Several other reports did not respond to the Cast but returned correctly after using an expression conversion of VAL().  I still have several reports that are not responding to either.  If anyone out there has a good explanation for this I'd love to hear it.