Error 500 when POST sent to ASPX page on my web site

[John30]

I have a POST from my eCommerce site to an ASPX web page on my GoDaddy hosted site. It links to a database and then generates an email license message. The problem is some of these POSTs are not getting through, returning an Error 500 to the eCommerce site. This all worked fine on my prior hosting company. I have a number of questions around this on Plesk:

1. IIS Settings, should Require SSL be checked?
2. IIS Application pool, Pipeline pool selection, classic or integrated?
3. IIS application pool, When recycle?
4. Https POST, anyone know anything about user/password requirements?
5. Where should web.config be, httpdocs or root?
6. Web.config redirect code impact to asp.net pages?
7. Is there anything unique to an SSL site that needs to be added to the POST message header or body?

I've been at this problem since the SSL was installed - worked fine before that.

[John30 · Accepted solution]

If anyone is having similar problems with POST, there is a terrific open source utility called Postman at postman.org that allowed me to get to the root of the problem I was having. Highly recommended