htaccess mod_rewrite: Simplifying URL - apache

Question

I've been having trouble with the following rewrite. I'm certain mod_rewrite is enabled but not sure where I am going wrong.
I'm try to change the following pattern:
/profile/?userid=157&username=FirstL
to:
/profile/FirstL
I've tried many different rules, but the two I felt were the closest to being correct aren't working at all. My current failures below:
RewriteEngine On
RewriteCond %{THE_REQUEST} \ /profile/+\?userid=$([^&\ ]+)&username=$([^&\ ]+)
RewriteRule ^ /%1? [L,R=301]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^([^/]+)$ /profile/?userid=$1&username=$2 [L,QSA]
 
RewriteEngine On
RewriteRule ^([^/]*)$ /profile/?userid=$1&username=$2 [L]
Full htaccess:
Options +FollowSymLinks -Multiviews
RewriteEngine On
RewriteCond %{THE_REQUEST} \ /profile/+\?userid=$([^&\ ]+)&username=$([^&\ ]+)
RewriteRule ^ /profile/%1/%2? [L,R=301]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^profile/([^/]+)/([^/]+)$ /profile/?userid=$1&username=$2 [L,QSA]
RewriteBase /
DirectorySlash Off
RewriteRule ^admin$ /admin/index.php [L,E=LOOP:1]
RewriteCond %{ENV:REDIRECT_LOOP} !1
RewriteRule ^admin/index.php$ /admin [R=301,L]
# remove .php
RewriteCond %{THE_REQUEST} ^GET\ (.*)\.php\ HTTP
RewriteRule (.*)\.php$ $1 [R=301]
# remove index
RewriteRule (.*)/index$ $1/ [R=301]
# remove slash if not directory
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_URI} /$
RewriteRule (.*)/ $1 [R=301]
# add .php to access file, but don't redirect
RewriteCond %{REQUEST_FILENAME}.php -f
RewriteCond %{REQUEST_URI} !/$
RewriteRule (.*) $1\.php [L]
#Force non-www:
RewriteCond %{HTTP_HOST} www.(.*)$ [NC]
RewriteRule ^(.*)$ http://%1/$1 [R=301,L]

Answer 1

You're losing the userID part of the URL, so when you try to internally rewrite that back, there's nothing there:
RewriteRule ^([^/]+)$ /profile/?userid=$1&username=$2 [L,QSA]
This rule says the first match is the "userid" and the second match is the "username", and you only have one match, and on top of that, it doesn't even begin with "profile".
You'll need to include the userid somewhere in the URL, otherwise there's no way to extract it.
RewriteEngine On
RewriteCond %{THE_REQUEST} \ /profile/+\?userid=([^&\ ]+)&username=([^&\ ]+)
RewriteRule ^ /profile/%1/%2? [L,R=301]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^profile/([^/]+)/([^/]+)$ /profile/?userid=$1&username=$2 [L,QSA]