UpdateException during upgrade from 12.0.1 to 12.0.4

First, I’m sorry for my bad English…
I try to explain what happened
On Jan, 9 I tried to update my nextcloud instance from 12.0.1 to 12.0.4 using web update procedure. At stage 4 the procedure stopped and now I cannot access to my web panel nor as admin.
The big problem is that I install my nextcloud instance on my hosting (host.it) and I cannot access via shell (no occ).
So, I have ftp and myphpadmin access but only this.

The error is here: https://pastebin.com/TEhR36uZ

Is it possible restore my instance and retry to update? Or…
I backedup all my file but not my contacts and calendar, is it possible recover from database may contacts and calendar events?
Thanks a lot for any help can you give me.

Nextcloud version (eg, 12.0.2): 12.0.1
Operating system and version (eg, Ubuntu 17.04): RHEL 2.6.32-642.6.2.el6.x86_64
Apache or nginx version (eg, Apache 2.4.25):
PHP version (eg, 7.1): 5.6.17

Download the config.php via ftp and set the maintenance mode to false. Upload the config.php file again and now youshloudbe able to get into your nc instance again. Then try to update again.