How to open another php file on server?

Question

PHP

The essence of the question is this. You need to upload the file adminer.php to the server and open it in a browser. I upload to the server, I try to open it, it gives an error "Error 404 Unable to process the request "adminer.php."". What could be the problem? apache limit or htaccess file? If you upload another file with the php extension, it also does not open, the pictures open

RewriteEngine on
RewriteRule ^index\.php - [L]
RewriteCond %{REQUEST_URI} !backend/
RewriteRule !\.(sql|gif|css|jpg|jpeg|png|ico|txt|js|xls|pdf|dtd|fck|csv|doc|rtf|swf|flv|cur|zip|rar|GIF|JPG|JPEG|PNG|XLS|PDF|DOC|xml|ttf|otf|eot|woff|svg|sql|jar|map|scss|woff2)$ /index.php

Answer 1

what are the rules in htaccess? Perhaps all requests go to one index.php file, for example.

Answer 2

try adding at the beginning
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d