Many readers left comments under the previous article saying that Flarum returns errors such as 404 on Nginx. This appears to be because the rewrite rules were not configured properly. The official documentation provides a detailed introduction to configuring Flarum rewrite rules in various environments. The Nginx rule is:

include /path/to/flarum/.nginx.conf;

This means pointing to the .nginx.conf file in the Flarum root directory. The advantage is that you do not need to consider whether the rewrite rules need to be updated each time Flarum is updated. However, you can also directly enter the contents of the .nginx.conf file in the rewrite rules settings of the BT panel.

Below are Flarum rewrite rules for three common environments.

Apache

<IfModule mod_rewrite.c>
  RewriteEngine on

  # Ensure the Authorization HTTP header is available to PHP
  RewriteRule .* - [E=HTTP_AUTHORIZATION:%{HTTP:Authorization}]

  # Uncomment the following lines if you are not using a `public` directory
  # to prevent sensitive resources from being exposed.
  # RewriteRule /\.git / [F,L]
  # RewriteRule ^composer\.(lock|json)$ / [F,L]
  # RewriteRule ^config.php$ / [F,L]
  # RewriteRule ^flarum$ / [F,L]
  # RewriteRule ^storage/(.*)?$ / [F,L]
  # RewriteRule ^vendor/(.*)?$ / [F,L]

  # Pass requests that don't refer directly to files in the filesystem to index.php
  RewriteCond %{REQUEST_FILENAME} !-f
  RewriteCond %{REQUEST_FILENAME} !-d
  RewriteRule ^ index.php [QSA,L]
</IfModule>

# Disable directory listings
Options -Indexes

# MultiViews can mess up our rewriting scheme
Options -MultiViews

# The following directives are based on best practices from H5BP Apache Server Configs
# https://github.com/h5bp/server-configs-apache

# Expire rules for static content
<IfModule mod_expires.c>
  ExpiresActive on
  ExpiresDefault                                      "access plus 1 month"
  ExpiresByType text/css                              "access plus 1 year"
  ExpiresByType application/atom+xml                  "access plus 1 hour"
  ExpiresByType application/rdf+xml                   "access plus 1 hour"
  ExpiresByType application/rss+xml                   "access plus 1 hour"
  ExpiresByType application/json                      "access plus 0 seconds"
  ExpiresByType application/ld+json                   "access plus 0 seconds"
  ExpiresByType application/schema+json               "access plus 0 seconds"
  ExpiresByType application/vnd.geo+json              "access plus 0 seconds"
  ExpiresByType application/vnd.api+json              "access plus 0 seconds"
  ExpiresByType application/xml                       "access plus 0 seconds"
  ExpiresByType text/calendar                         "access plus 0 seconds"
  ExpiresByType text/xml                              "access plus 0 seconds"
  ExpiresByType image/vnd.microsoft.icon              "access plus 1 week"
  ExpiresByType image/x-icon                          "access plus 1 week"
  ExpiresByType text/html                             "access plus 0 seconds"
  ExpiresByType application/javascript                "access plus 1 year"
  ExpiresByType application/x-javascript              "access plus 1 year"
  ExpiresByType text/javascript                       "access plus 1 year"
  ExpiresByType application/manifest+json             "access plus 1 week"
  ExpiresByType application/x-web-app-manifest+json   "access plus 0 seconds"
  ExpiresByType text/cache-manifest                   "access plus 0 seconds"
  ExpiresByType text/markdown                         "access plus 0 seconds"
  ExpiresByType audio/ogg                             "access plus 1 month"
  ExpiresByType image/bmp                             "access plus 1 month"
  ExpiresByType image/gif                             "access plus 1 month"
  ExpiresByType image/jpeg                            "access plus 1 month"
  ExpiresByType image/png                             "access plus 1 month"
  ExpiresByType image/svg+xml                         "access plus 1 month"
  ExpiresByType image/webp                            "access plus 1 month"
  ExpiresByType video/mp4                             "access plus 1 month"
  ExpiresByType video/ogg                             "access plus 1 month"
  ExpiresByType video/webm                            "access plus 1 month"
  ExpiresByType application/wasm                      "access plus 1 year"
  ExpiresByType font/collection                       "access plus 1 month"
  ExpiresByType application/vnd.ms-fontobject         "access plus 1 month"
  ExpiresByType font/eot                              "access plus 1 month"
  ExpiresByType font/opentype                         "access plus 1 month"
  ExpiresByType font/otf                              "access plus 1 month"
  ExpiresByType application/x-font-ttf                "access plus 1 month"
  ExpiresByType font/ttf                              "access plus 1 month"
  ExpiresByType application/font-woff                 "access plus 1 month"
  ExpiresByType application/x-font-woff               "access plus 1 month"
  ExpiresByType font/woff                             "access plus 1 month"
  ExpiresByType application/font-woff2                "access plus 1 month"
  ExpiresByType font/woff2                            "access plus 1 month"
  ExpiresByType text/x-cross-domain-policy            "access plus 1 week"
</IfModule>

# Gzip compression
<IfModule mod_deflate.c>
  <IfModule mod_filter.c>
    AddOutputFilterByType DEFLATE "application/atom+xml" \
                                  "application/javascript" \
                                  "application/json" \
                                  "application/ld+json" \
                                  "application/manifest+json" \
                                  "application/rdf+xml" \
                                  "application/rss+xml" \
                                  "application/schema+json" \
                                  "application/vnd.geo+json" \
                                  "application/vnd.ms-fontobject" \
                                  "application/wasm" \
                                  "application/x-font-ttf" \
                                  "application/x-javascript" \
                                  "application/x-web-app-manifest+json" \
                                  "application/xhtml+xml" \
                                  "application/xml" \
                                  "font/collection" \
                                  "font/eot" \
                                  "font/opentype" \
                                  "font/otf" \
                                  "font/ttf" \
                                  "image/bmp" \
                                  "image/svg+xml" \
                                  "image/vnd.microsoft.icon" \
                                  "image/x-icon" \
                                  "text/cache-manifest" \
                                  "text/calendar" \
                                  "text/css" \
                                  "text/html" \
                                  "text/javascript" \
                                  "text/plain" \
                                  "text/markdown" \
                                  "text/vcard" \
                                  "text/vnd.rim.location.xloc" \
                                  "text/vtt" \
                                  "text/x-component" \
                                  "text/x-cross-domain-policy" \
                                  "text/xml"
    </IfModule>
</IfModule>

# Fix for https://httpoxy.org vulnerability
<IfModule mod_headers.c>
  RequestHeader unset Proxy
</IfModule>

Nginx

# Pass requests that don't refer directly to files in the filesystem to index.php
location / {
  try_files $uri $uri/ /index.php?$query_string;
}

# The following directives are based on best practices from H5BP Nginx Server Configs
# https://github.com/h5bp/server-configs-nginx

# Expire rules for static content
location ~* \.(?:manifest|appcache|html?|xml|json)$ {
  add_header Cache-Control "max-age=0";
}

location ~* \.(?:rss|atom)$ {
  add_header Cache-Control "max-age=3600";
}

location ~* \.(?:jpg|jpeg|gif|png|ico|cur|gz|svg|mp4|ogg|ogv|webm|htc)$ {
  add_header Cache-Control "max-age=2592000";
  access_log off;
}

location ~* \.(?:css|js)$ {
  add_header Cache-Control "max-age=31536000";
  access_log off;
}

location ~* \.(?:ttf|ttc|otf|eot|woff|woff2)$ {
  add_header Cache-Control "max-age=2592000";
  access_log off;
}

# Gzip compression
gzip on;
gzip_comp_level 5;
gzip_min_length 256;
gzip_proxied any;
gzip_vary on;
gzip_types
    application/atom+xml
    application/javascript
    application/json
    application/ld+json
    application/manifest+json
    application/rss+xml
    application/vnd.geo+json
    application/vnd.ms-fontobject
    application/x-font-ttf
    application/x-web-app-manifest+json
    application/xhtml+xml
    application/xml
    font/opentype
    image/bmp
    image/svg+xml
    image/x-icon
    text/cache-manifest
    text/css
    text/plain
    text/vcard
    text/vnd.rim.location.xloc
    text/vtt
    text/x-component
    text/x-cross-domain-policy;

Caddy

www.example.com {
    root /var/www/flarum/public
    rewrite {
        to {path} {path}/ /index.php
    }
    fastcgi / /var/run/php/php7.2-fpm.sock php
    header /assets {
        +Cache-Control "public, must-revalidate, proxy-revalidate"
        +Cache-Control "max-age=25000"
        Pragma "public" 
    }
    gzip
}