500 server error caused by htaccess - .htaccess

Question

I'm writing an htaccess for handeling my links for seo friendly links. But now suddenly it says an 500 Internal Server Error?? Is there a limit on lines for htaccess?
.htaccess:
ErrorDocument 404 /404/404.html
Options +FollowSymLinks -MultiViews
# Turn mod_rewrite on
RewriteEngine On
RewriteRule ^choose/[a-zA-Z0-9]+)/?$ choose.php?gebruikersnaam=$1 [L,QSA,NC]
blabla, some stuff you don't need to see anymore.

Answer 1

There is a few ways to debug why your .htaccess is not working, the fastest one is if you have access to the web server config file so you can turn on RewriteLog which will pinpoint where it fails for you:
RewriteLog "/path_to_save_it/rewrite_log"
RewriteLogLevel 9
Another way would be by placing your rules inside IfModule directive:
<IfModule mod_rewrite.c>
# your rule comes here
</IfModule>
For example:
Options +FollowSymLinks -MultiViews
<IfModule mod_rewrite.c>
ErrorDocument 404 /404/404.html
# Turn mod_rewrite on
RewriteEngine On
RewriteRule ^show/([0-9]+)/?$ show.php?photo=$1 [L,QSA,NC]
RewriteRule ^report/([0-9]+)/?$ report.php?photo=$1 [L,QSA,NC]
RewriteRule ^index/?$ index.php [L,QSA,NC]
RewriteRule ^album/?$ album.php [L,QSA,NC]
RewriteRule ^choose/?$ choose.php [L,QSA,NC]
RewriteRule ^choose/[a-zA-Z0-9]+)/?$ choose.php?gebruikersnaam=$1 [L,QSA,NC]
RewriteRule ^rules/?$ rules.php [L,QSA,NC]
RewriteRule ^winners/?$ winners.php [L,QSA,NC]
RewriteRule ^contact/?$ contact.php [L,QSA,NC]
RewriteRule ^forget-password/?$ password.php [L,QSA,NC]
RewriteRule ^forget-password/([a-zA-Z0-9]+)/([a-zA-Z0-9]+)/?$ password.php?gebruiker=$1&wachtwoord=$2 [L,QSA,NC]
RewriteRule ^upload-picture/?$ upload.php [L,QSA,NC]
RewriteRule ^user-cp/?$ user-photo.php [L,QSA,NC]
RewriteRule ^user-cp/delete/([0-9]+)/?$ user-photo.php?delete=$1 [L,QSA,NC]
RewriteRule ^user-cp/yes/([0-9]+)/?$ user-photo.php?yes=$1 [L,QSA,NC]
RewriteRule ^logout/?$ logout.php [L,QSA,NC]
RewriteRule ^mail-second/?$ mail_second.php [L,QSA,NC]
RewriteRule ^activate/?$ activate.php [L,QSA,NC]
RewriteRule ^activate/([a-zA-Z0-9]+)/([a-zA-Z0-9]+)/?$ activate.php?code=$1&gebruikersnaam=$2 [L,QSA,NC]
</IfModule>
If all your rules have no issue but mod_rewrite is not enabled you will get no errors so you will know mod_rewrite is not enable if you try any rules.
If you still get error then it means mod_rewrite is enable and 1 or more rules are right, like missing something perhaps.
However from the above you will only know you have a problem, by using the elimination method you will find the exact line or lines that are causing the issue, which is by commenting all lines and then uncomment one by one, testing what that line is supposed to do before moving to the next line.
This way you will pinpoint where the problem is.