Is it possible to go back to the last update?
Many apps stopped working.
If possible we would have time to modify the updates and then update again

You cannot go back to a prior version without restoring from backup which can result in a loss of data. 

There is an optional patch that can be installed that allows 3rd party apps to still run (but provides a warning in the ACP).  I would recommend installing it. 

Where can I find that patch and how can I run it?

If you go to support in your admin CP, you will see the optional patch showing in the box in the top left