I got 500 internal server error after changing wordpress permalinks. It gives me the same error for all the options except the plain one.
The error is only on the post pages. Many people say that wordpress is not allowed to edit .htaccess file. However, I have a plugin which edited my .htaccess file successfully.
Two more things that might be important I use proxy to run the blog and here is what inside .htaccess file
# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /news/
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /news/index.php [L]
</IfModule>
# END WordPress

.htaccess? - Farside[Fri Jul 08 04:48:24.237062 2016] [core:error] [pid 2430] [client 46.101.144.77:36922] AH00124: Request exceeded the limit of 10 internal redirects due to probable configuration error. Use 'LimitInternalRecursion' to increase the limit if necessary. Use 'LogLevel debug' to get a backtrace., referer: http://6-cylinder.com/news/- amronrails