Data import fails in CRM Online 2015 : An error has occurred

Hi,

I am trying to import data (through CSV or Excel files) on CRM Online, and it fails.

I got a generic error : An error has occurred. Try this action again. If the problem continues, check the Microsoft Dynamics CRM Community for solutions or contact your organization's Microsoft Dynamics CRM Administrator. Finally, you can contact Microsoft Support.

I had tried different solutions :

1) Different import format (.xls, .xlsx, .csv)

2) Testing the import of different entities

3) Delete all rows of the file and keep only one record to import (with simple data)

And the size of the file is less than 8 MG. I has search on the Community Portal and haven't found a solution.

Can you help me?

Thanks!