Updater Problem: Timeout during Backup: Update from 12.0.1 to 12.0.2

*During the update from 12.0.1 to 12.0.2 I got the following error:
(Had same error before during update from 11.0.2? to 12.0.1)

Create backup
Parsing response failed. <html> <head><title>504 Gateway Time-out</title></head> <body bgcolor="white"><center><h1>504 Gateway Time-out</h1></center> <hr><center>nginx</center> </body> </html>

*After click “retry update” same error again.
*Again click “retry update” shortly after the error pops up, it shows:

Create backup
Parsing response failed. Step 4 is currently in process. Please reload this page later.
  • Reload page: Page is in maintenance mode.
  • config.php -> set mantanance mode off
  • Open updater again: Create Backup shows (OK)
  • Click “Continue Update”
  • Update finishes successfully

I have the same problem with update from nexcloud 12.0.4 to 13.0.1
but, after 1 week, i always have the message “Step 4 is currently in process. Please reload this page later.” launching the update from the admin panel or from the updater directory …

my nextcloud is on a mutualized hosting at OVH

PHP

Version: 7.0.27
Memory Limit: 536870912
Max Execution Time: 3600
Upload max size: 511 MB

Database

Type: mysql
Version: 5.6.34
Size: 2.7 MB

I have this errors in logging:
|Error|PHP|Zend OPcache API is restricted by “restrict_api” configuration directive at /home/[…]/cloud/lib/private/legacy/util.php#1369 x 3 times
|Error|PHP|Function create_function() is deprecated at /home/[…]/cloud/lib/private/Route/Route.php#155 x 10 or more times

i have made maintenance mode off in config.php, but i still have the problem.
is there other thing to do to restart the updating process from the beginning ?

edit

in config/config.php i change ‘maintenance’ to false
in data i remove the directory updater-[…]
and after that i could run again the updater and it works fine