Upgrate MySQL5.5 to 5.7 under Windows
Tmptr C

a. Backup the database using tools like command-line or Navicat UI to import the DB SQL.
b. Download the MySQL ver5.7 green version from the official website.
c. Use admin privileges to open the command line and execute the following commands:

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mysqld -install
mysqld --initialize-insecure --user=mysql
net start mysql // If your service name is mysql

Setting the new password for root:

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mysqld --skip-grant-tables
Jump to another new command line window, execute the `mysql` command
Input the following on the `mysql>` prompt:
update mysql.user set authentication_string=password("newpassword") where user="root";
flush privileges;

d. Create a new INI config file:

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[mysqld]
port = 3306
basedir=D:\mysql-5.7.43-winx64
datadir=D:\mysql-5.7.43-winx64\data
max_connections=150
character-set-server=utf8
default-storage-engine=INNODB
sql_mode=NO_ENGINE_SUBSTITUTION // For previous compatibility, importantly
explicit_defaults_for_timestamp=0 // For previous compatibility, importantly
event_scheduler=ON
max_allowed_packet=256M
sort_buffer_size=3M
#log_error=D:\mysql-5.7\error.log // Debug if open
[mysql]

Once all the above steps are completed smoothly, you can proceed to import your database SQL and data using the backup files.