I filed an extension and it was accepted ( documentation attached) when I was using Window 7.  Upgraded to Windows 10 and then transmitted the actual federal tax return.  The CA return went through just fine.  The only acknowledge for the federal return was "No Valid First Extension EF Center Record Exists for this SSN/EIN".  How can I determine if this return was accepted by the IRS?  What must be fixed if it hasn't?.