Hi grupodeca, I had the same problem on my shared hosting, so I don't have access to the server.
I solved the problem following this steps:
- Download the file
http://curl.haxx.se/ca/cacert.pem
- Rename it as "cert.pem" and put in a folder (in my case, just "certs")
- Edited PHP.ini and added this line
openssl.cafile = "/complete/path/to/the/root/site/folder/certs/cert.pem"
I took the solution from:
https://akrabat.com/ssl-certificate-verification-on-php-5-6/
Then you retry the upgrade and it should work. Regards!