Salve,
probabilmente alcune impostazione del sito vecchio non sono compatibili con il sito nuovo, le lascio alcune istruzioni per il debug
A white page or a page with a 500 Internal Server Error is, in fact, either a .htaccess issue to a PHP fatal error in disguise.
First, let's see if it is a .htaccess issue. Try renaming the .htaccess file in your site's root to htaccess.bak This disables WordPress' permalinks. To re-enable them go to your site's wp-admin, Settings, Permalinks and note down which of the "Common Settings" option is selected. Now select a different Common Settings option and click on Save Changes at the bottom of the change. Now change it back to your previous option and click on Save Changes again. This little dance with WordPress options instructs WordPress to regenerate its default .htaccess which does not conflict with anything and is used to enable permalinks.
If that solved the problem, the issue was with a directive in your .htaccess file. We'd like to recommend you to try removing directives from your .htaccess until you find the one which causes the problem.
If that doesn't help, the error you are receiving is in fact a PHP error in disguise. First, check your server's error logs (not the access logs) immediately after visiting the page which throws the error. There should be an exact description of the PHP fatal error which occurred. Sometimes you can find the error messages in files called error_log or error.log inside the site's root, the wp-admin directory or wherever the .php file which produces the blank page is located. If unsure about the error log location, please consult your host. Most likely the error logs are available in your site's hosting control panel.
If your host does not give you access to the error logs you will need to edit your site's wp-config.php file to enable WP_DEBUG. Find the line reading
define( 'WP_DEBUG', false );
and change it to
define( 'WP_DEBUG', true );
If no such line exists on your site's wp-config.php file please append that line at the end of the file. Do remember to reverse this change after you're done debugging!
If you still get a white page, please create a file called php.ini with the following content:
display_errors=on
error_reporting=E_ALL
and upload it into your site's root and your site's administrator directory. If the file already exists edit the existing file instead of replacing it. Retry loading the problem page.
If that fails again create a file named .user.ini (note that it's dot user dot ini, the leading dot is important) with the contents:
display_errors=on
error_reporting=E_ALL
and upload it into your site's root and your site's administrator directory. If the file already exists edit the existing file instead of replacing it. Wait for 10 minutes. Waiting is important, .user.ini files do not apply immediately. Retry loading the problem page.
If you still get a white page, remove the php.ini or .user.ini file your created (or the changes you made to these files) and consult your host. They have to provide you the PHP error message, file and line it occurs (along with the error's backtrace) themselves.
Please note that if you can not understand what the PHP error message means, just copy and paste it here verbatim so that we can take a look and point you to the right direction.
Davide Tampellini
Developer and Support Staff
🇮🇹Italian: native 🇬🇧English: good • 🕐 My time zone is Europe / Rome (UTC +1)
Please keep in mind my timezone and cultural differences when reading my replies. Thank you!