HTTP error 500 - htaccess file related - .htaccess

Question

My website is currently giving me a HTTP error 500. It seems to be the frontend that is not working, as the backend (/admin) works as do the emails and subdomains which are on the same VPS. I have contacted my host and they have told me they have no errors their side so it must be my side.
My htaccess file currently reads:
order allow,deny
deny from 188.143.232.
allow from all
<ifModule mod_gzip.c>
mod_gzip_on Yes
mod_gzip_dechunk Yes
mod_gzip_item_include file .(html?|txt|css|js|php|pl)$
mod_gzip_item_include handler ^cgi-script$
mod_gzip_item_include mime ^text/.*
mod_gzip_item_include mime ^application/x-javascript.*
mod_gzip_item_exclude mime ^image/.*
mod_gzip_item_exclude rspheader ^Content-Encoding:.*gzip.*
</ifModule>
# 1.To use URL Alias you need to be running apache with mod_rewrite enabled.
# 2. In your opencart directory rename htaccess.txt to .htaccess.
# For any support issues please visit: http://www.opencart.com
Options +FollowSymlinks
# Prevent Directoy listing
Options -Indexes
# SEO URL Settings
RewriteEngine On
# If your opencart installation does not run on the main web folder make sure you folder it does run in ie. / becomes /
#RewriteBase /
#RewriteRule ^sitemap.xml$ index.php?route=feed/google_sitemap [L]
#RewriteRule ^googlebase.xml$ index.php?route=feed/google_base [L]
#RewriteRule ^download/(.*) /index.php?route=error/not_found [L]
#RewriteRule ^image-smp/(.*) index.php?route=product/smp_image&name=$1 [L]
#RewriteCond %{REQUEST_FILENAME} !-f
#RewriteCond %{REQUEST_FILENAME} !-d
#RewriteCond %{REQUEST_URI} !.*\.(ico|gif|jpg|jpeg|png|js|css)
RewriteRule ^([^?]*) index.php?_route_=$1 [L,QSA]
### Additional Settings that may need to be enabled for some servers
### Uncomment the commands by removing the # sign in front of it.
### If you get an "Internal Server Error 500" after enabling any of the following settings, restore the # as this means your host doesn't allow that.
# 1. If your cart only allows you to add one item at a time, it is possible register_globals is on. This may work to disable it:
#php_flag register_globals off
# 2. If your cart has magic quotes enabled, This may work to disable it:
#php_flag magic_quotes_gpc Off
# 3. Set max upload file size. Most hosts will limit this and not allow it to be overridden but you can try
#php_value upload_max_filesize 999M
# 4. set max post size. uncomment this line if you have a lot of product options or are getting errors where forms are not saving all fields
#php_value post_max_size 999M
# 5. set max time script can take. uncomment this line if you have a lot of product options or are getting errors where forms are not saving all fields
#php_value max_execution_time 200
# 6. set max time for input to be recieved. Uncomment this line if you have a lot of product options or are getting errors where forms are not saving all fields
#php_value max_input_time 200
# 7. disable open_basedir limitations
#php_admin_value open_basedir none
Upon troubleshooting I commented out the line:
RewriteRule ^([^?]*) index.php?_route_=$1 [L,QSA]
This allowed the website to work, or so I thought until this morning, as it's back to giving me the HTTP error 500.
I'm pretty sure the error is somewhere in this file, but I dont understand what could have triggered it as it's been working fine prior to any changes being made to it.
Please any advice would be appreciated, I'm very new to this & would be really grateful for anyone's help.
Thanks
Paul

Answer 1

try to add
before:
RewriteBase /
after:
RewriteBase /Sitename
Hope it helps.