MS CRM 2013 on-Premise to 2015 on-Premise Upgrade

Hi,

while MS CRM 2013 on-Premise to 2015 on-Premise Upgrade I got below error :

Error : You can only import solutions with a package version of 7.0 or earlier into this organization. Also you can't import any solution into this organization that were exported from MS CRM 2011 or earlier.

Please suggest anyone .

Note : I done MS CRM 2013 on-Premise to 2015 online Upgrade Successfully. 

Cheers,

Kannan. S