Internal Server Error (port 443)

Please check server’s error log
Most likely its a .htaccess error, because you can solve it with permalinks reset.

Also please show your .htaccess file content (when it cause error 500)

I dont understand, what should I do? Please give the instruction step by step.

Find apache’s error.log (ask your hosting support where to find it, or for its content), look for errors at the end of file.

Error 500 can be caused by PHP and sometimes by apache (when .htaccess contains incorrect rules)

Download .htaccess from your server (by FTP/SFTP, you can use FileZilla or by using hosting control panel File Manager)

Post content of this file here ( Please enclose its content it CODE tags for proper formatting )

# BEGIN rlrssslReallySimpleSSL rsssl_version[3.2.3]
<IfModule mod_rewrite.c>
RewriteEngine on
RewriteCond %{HTTPS} !=on [NC]
RewriteRule ^(.*)$ https://%{HTTP_HOST}/$1 [R=301,L]
</IfModule>
# END rlrssslReallySimpleSSL
# BEGIN WordPress
# The directives (lines) between "BEGIN WordPress" and "END WordPress" are
# dynamically generated, and should only be modified via WordPress filters.
# Any changes to the directives between these markers will be overwritten.
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteRule .* - [E=HTTP_AUTHORIZATION:%{HTTP:Authorization}]
RewriteBase /
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>

# END WordPress

• This reply was modified 3 years, 11 months ago by Yui. Reason: please use CODE button for proper formatting

This is .htaccess file

Your .htaccess seem to be valid syntax,
so please check the error.log

I dont know where its placed. Hosting company is closed today.