PHP 升级后出现 503 Service Unavailable 错误

如何解决PHP 升级后出现 503 Service Unavailable 错误

将 PHP 升级到 7.4 版本后，出现以下错误：

Service Unavailable

The server is temporarily unable to service your request due to maintenance downtime or capacity problems. Please try again later.

Additionally,a 503 Service Unavailable error was encountered while trying to use an ErrorDocument to handle the request.

我尝试了所有解决方案，例如停用插件和更改主题。两者都不起作用。

我认为它可能与.htaccess文件有关，因为我只能在评论http的一部分后才能使用.htaccess查看主页。

这是我的.htaccess：

RewriteCond %{HTTPS} off
RewriteRule .* https://%{HTTP_HOST}%{REQUEST_URI} [L,R=301]
RewriteCond %{HTTP_HOST} !^www\. [NC]
RewriteRule .* https://www.%{HTTP_HOST}%{REQUEST_URI} [L,R=301]
# 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
    
# SET CACHE
<IfModule mod_rewrite.c>
    <FilesMatch "\.(ico|pdf|flv|jpg|jpeg|png|gif|swf|eot|woff2|woff|ttf|svg)$">
    Header set Cache-Control "max-age=31449600,public"
    </FilesMatch>
    <FilesMatch "\.(xml|txt|js|css|json)$">
    Header set Cache-Control "max-age=604800,public,must-revalidate"
    </FilesMatch>
    <FilesMatch "\.(html|htm|PHP)$">
    Header set Cache-Control "max-age=28800,must-revalidate"
    </FilesMatch>
</IfModule>
# ZIP IMAGES
<IfModule mod_deflate.c>
SetoutputFilter DEFLATE
browserMatch ^Mozilla/4 gzip-only-text/html
browserMatch ^Mozilla/4\.0[678] no-gzip
browserMatch \bMSI[E] !no-gzip !gzip-only-text/html
SetEnvIfNoCase Request_URI \
\.(?:gif|jpe?g|png)$ no-gzip dont-vary
Header append vary User-Agent env=!dont-vary
</IfModule>

# PHP -- BEGIN cPanel-generated handler,do not edit
# Set the “ea-PHP74” package as the default “PHP” programming language.
<IfModule mime_module>
  AddHandler application/x-httpd-ea-PHP74 .PHP .PHP7 .phtml
</IfModule>
# PHP -- END cPanel-generated handler,do not edit

我评论了这部分：

#RewriteCond %{HTTPS} off
#RewriteRule .* https://%{HTTP_HOST}%{REQUEST_URI} [L,R=301]
#RewriteCond %{HTTP_HOST} !^www\. [NC]
#RewriteRule .* https://www.%{HTTP_HOST}%{REQUEST_URI} [L,R=301]

之后我可以访问http://mywebsite.com，但是子页面不能只在主页上工作。

我有一个名为 test 的子域，如果有帮助的话。

如何解决这个问题？