Stuck at "MySQL server has gone away" at the exact same point during upgrade

I have tried to upgrade from 2.4.8 to 3.0.2, but every time I am stuck at this line:

(mysqli): ALTER TABLE subscription_types MODIFY COLUMN disable_public_display TINYINT NOT NULL

The process sits there for over a day, and when it continues, sooner or later it ends at the same place:

Query: UPDATE signoffs SET assoc_type = 1048585 WHERE assoc_type = 257 failed. MySQL server has gone away
2006: MySQL server has gone away

ADOConnection._Execute(UPDATE signoffs SET assoc_type = 1048585 WHERE assoc_type = 257, false) % line 1051, file: [adodb.inc.php](file:///C:/xampp/htdocs/journal/lib/pkp/lib/adodb/adodb.inc.php) ADOConnection.Execute(UPDATE signoffs SET assoc_type = 1048585 WHERE assoc_type = 257) % line 440, file: [Installer.inc.php](file:///C:/xampp/htdocs/journal/lib/pkp/classes/install/Installer.inc.php) Installer.executeSQL(UPDATE signoffs SET assoc_type = 1048585 WHERE assoc_type = 257) % line 435, file: [Installer.inc.php](file:///C:/xampp/htdocs/journal/lib/pkp/classes/install/Installer.inc.php) Installer.executeSQL(Array[15]) % line 396, file: [Installer.inc.php](file:///C:/xampp/htdocs/journal/lib/pkp/classes/install/Installer.inc.php) Installer.executeAction(Array[3]) % line 265, file: [Installer.inc.php](file:///C:/xampp/htdocs/journal/lib/pkp/classes/install/Installer.inc.php)

I am on Windows Server 2016, XAMPP 7.2.5 and I increased various limits to this, at no avail:

in MySQL.ini:
max_allowed_packet=100M
read_buffer_size=2048M

in PHP.ini:
max_execution_time=12000
max_input_time=6000
memory_limit=512M
post_max_size=400M
upload_max_filesize=300M
default_socket_timeout=6000

What can I do to finish the upgrade?