Why is there an error in the .htaccess file?

Question

Apache HTTP Server

AddDefaultCharset UTF-8

RewriteRule ^about?$ about.php [NC, L]
RewriteRule ^404?$ 404.php [NC, L]

ErrorDocument 404 /404

I registered the following conditions, an error occurs on the server Internal Server Error, what am I doing wrong?

Answer 1

Syntax error here [NC, L]
Flags must be listed separated by commas without extra spaces[NC,L]