For all who has the same problem...
First of all - I found that it is a Azure related problem...
https://docs.microsoft.com/en-us/azure/mysql/concepts-limits
First of all - I found that it is a Azure related problem...
https://docs.microsoft.com/en-us/azure/mysql/concepts-limits
Current known issues
And finally to resolve it I changed the get_server_info method in lib/dml/mysqli_native_moodle_database.php to look like this:
public function get_server_info() {
$res = $this->mysqli->query("SELECT VERSION() AS VERSION;");
$res->data_seek(0);
$data = $res->fetch_array();
return array('description'=>$data["VERSION"], 'version'=>$data["VERSION"]);
}