Updating From 3.1.1-4 to 3.1.2-1

I successfully update OJS system. And had practical cases.
OJS 3.1.1-4 work best, PHP version was 5. (Journal have Ukrainian and Russian issues.
First I backup all data and database.
Then I change PHP to version 7.3
Then download new OJS 3.12-1 and edit file config.inc. Copy the server, database settings from old confg.inc to new.
The main moments are set
client_charset = utf-8
connection_charset = utf8
database_charset = utf8
force_ssl = On
force_login_ssl = On
Then PHP 7.3 requires change
driver = mysqli
In database PHPmyAdmin i set utf8_unicode_ci
Then i must delete Folder OpenAire from folder Plugins/Generic, because during upgrade I receive message about downgrading plugin.
This moments help me solve Internal server error 500, problem with correct show russian characters set, problem with stopping and freezing update.
Now all work.
This sites Pain medicine and Perioperative medicine