I’m a beginner to WordPress.

I had a machine use the wamp64 server and php v7.3.5 to build my WordPress site,
and I just click the upgrade button to set my WordPress version 5.4.4 to 5.6 form the dashboard.

After the upgrade is finished, the homepage didn’t show correctly.

I set the homepage information form "Settings -> Your homepage displays -> A static page -> Homepage" and choose the page I create it public.

But when I browse the homepage it show :

The following way that I had already try :

• Restart the wamp64 server.
• Stop all the plugin which is running in my WordPress.
• Change the theme.

And it also can’t show my homepage.

I had use the plugin "WP Downgrade" to recover my website to 5.4.4 and it works fine.

Is there any idea can let me upgrade my WordPress to v5.6 and fix or trace this problem?

Thanks for all your information.