I found that using the 404 and 405 method when using forms IIS would dump the data before MODx could process it which resulted in the forms not working.
If it’s a single site on your server you can use the ISAPI Rewrite lite version which is for one site only and free!!
Once you install this on your server or find a host who has it, the rest is very easy.
Point 404 and 405 to index.php
in the wwwroot folder create a file called "httpd.ini" and add the following contents
# 3600 = 1 hour
# Block external access to the httpd.ini and httpd.parse.errors files
RewriteRule /httpd(?:\.ini|\.parse\.errors).* / [F,I,O]
# Block external access to the Helper ISAPI Extension
RewriteRule .*\.isrwhlp / [F,I,O]
RewriteCond Method GET|HEAD
RewriteRule /(?!(?:manager|assets)/)(.*)\.html(?:\?(.*))? /index.php?q=$1?2&$2: [I,L,U]
Log into MODx manager -> Click Administration -> System Configuration -> Friendly URL Settings
My Settings are:
Use Friendly URLS = yes
Prefix for friendly URLS =
Suffic for friendly URLS = .html
Let me know how you get on, with the above settings FURLS work perfectly and in my webstats It logs the actual page name called and not a 404 error page, also forms work perfectly.