Error uploading file in Fiori My Inbox app

Hello,

Trying to upload a file into My inbox Fiori app with the upload function the system shows up the error 'Cannot upload file'. Looking at the HTML console the error shows as:

GET http://XXXXX/sap/bc/ui5_ui5/ui2/upload/index.html 404 (NOT FOUND)

looks as if it is trying to access an unexisting service..

My Client's MyInbox app Version is 1.6.4

I Applied notes to the same app in my company's system to upgrade version to 1.6.13 (lastest) but the problem still persists.

¿Does anyone know what the problem could be?

Thank you very much in advance,

Héctor