I have a similar problem. We have SharePoint intranet site with a form at "http://.../Forms/template.xsn". The same SharePoint site (and form) is accessible at "https://...../Forms/template.xsn" to employees not signed into VPN.
Using save functionality, I am able to add a form to the library from either http or https. But when I visit the external site (https://...) and open a form created from the internal site
http://), I get "Could not open
http://...../Forms/template.xsn". Visa Versa. The form saves ok though.
The test form is using jscript, but would like to get it to work using managed code.
Is there a way to suppress the error?
Is it possible to make the open/submit functionality work in this situation?