Installing Invoiceplane in a subfolder - "404 Error"

Support
12

So your htaccess should look like this:

<IfModule mod_rewrite.c>
  RewriteEngine On

  ### uncomment to force HTTPS
  RewriteCond %{HTTPS} off
  RewriteRule ^(.*)$ https://%{HTTP_HOST}/$1 [R=301,L]

  RewriteRule ^index\.php$ - [L]
  RewriteCond %{REQUEST_FILENAME} !-f
  RewriteCond %{REQUEST_FILENAME} !-d
  ### uncomment and adjust if installed in subdirectory
  RewriteRule . /invoice/index.php [L]
</IfModule>