.htaccess - Customize Internal Server Error apache -

i have moved site from, say, www.example.com/coretasks, coretasks.example.com, , i'd redirect visitors have been given link old site, new site.

i've been getting complaint error message "internal server error 500" or 404 error.

what i'm trying customize error inform them of fact site has been moved, , automatically redirect them right site after 5 seconds. have written small html code , named 500.html , 404.html.

in .htaccess file, have:

# begin wordpress <ifmodule mod_rewrite.c> rewriteengine on errordocument 500 /custom_template/500.html errordocument 404 /custom_template/404.html      rewritebase /     rewriterule ^index\.php$ - [l]     rewritecond %{request_filename} !-f     rewritecond %{request_filename} !-d     rewriterule . /index.php [l]     </ifmodule>      # end wordpress 

below have got in both 404.html , 500.html

<meta http-equiv="refresh" content="5; url=https://coretasks.example.com/"> 

but appears doesn't load either 500.html or 404.html.

just wonder if have missed out on here.

thank much