I tried to browse to the HostSample.html locally from the Internet explorer by browsing (C:\demo\Adobe Flash Builder 4.7\demo_hostsample\mpcui\bin-debug\HostSample.html) and was able to get to the UI loaded from Internet Explorer with the same details. The weird part is it works in some sessions and fails with the ioerror. Some online forums talk about hitting this error (http://forums.adobe.com/thread/1281685 ) and few also talk about some cross-domain issues as well. However, I was able to get it working in one of my IE sessions without encountering the cross-domain issue. Weird as it might sound though.
Atleast I can say that from the Flexbuilder, the request never makes it to the server. I profiled it via Charles to confirm this. However, from IE some sessions do succeed and some fail and the failure happens once the failure occurred in the launch from Flexbuilder.
When running with HTTPS, FlexBuilder enforces security restrictions on same domain policy and verifies security certificate. To workaround this you either have to disable security on your OMS and use HTTP for your development (using emctl secure unlock), or you have to install the security certificate from your OMS in the IE browser you are launching from FlexBuilder.
To install the certificate in Firefox: go to the EM website using Firefox, and you will see "The Connection is Untrusted", expand "I Understand the Risks" and click "Add Exception". On the dialog that appears leave all the defaults and click "Confirm Security Exception". At that point if you close/reopen the browser you can go back to the EM website and you should see no security exception.
To install the certificate in IE: go to the EM website using IE and you should see "There is a problem with this website's security certificate", click "Continue to this Website (not recommended)", the address bar will then change to show "Certificate error" on the right side of the URL. Click that icon and the "View certificates" on the "Untrusted Certificate" popup. On the dialog that appears, click the "Certification Path" tab, then click the root node (root certificate) in the path and click "View Certificate". In the new dialog that appears, click "Install Certificate...". Then click "Next>", click "Place all certificates in the following store", click "Browse..."., select "Trusted Root Certification Authorities" and click "OK". Then click "Next>" and click "Finish". On the "Security Warning" dialog, click "Yes" to install the certificate and then "OK on the confirmation dialog. Click "OK" on the "Certificate" dialog (there should be two) that was launched to install the root certificate. Now on the original "Certificate" dialog click "View Certificate". Then click "Next>", click "Place all certificates in the following store", click "Browse..."., select "Trusted Root Certification Authorities" and click "OK". Then click "Next>" and click "Finish" and then "OK on the confirmation dialog. Click "OK" and "OK". At that point if you close/reopen the browser you can go back to the EM website and you should see no security exception.
I tried the same, but it is not resolving the issue. Also from IE this works fine sometimes, however when i launch from FlexBuilder via run option, it launches the html file in IE. However, I end up seeing the same error
I still keep getting those errors. Not sure what is wrong. For some session, I can get the deployment right and for others I am unable to and get the ioError. Kindly let me know if u need any more information to help get around the issue.
The issue has to do with the certificate. If installing the certificate in IE is not working then I would suggest using another browser (Firefox) from FlexBuilder or reconfiguring your OMS to not require a secure connection. Use emctl secure unlock to do this. This error is related to the certificate and correctly installing the certificate should resolve it. Sorry I can't help much more than that on this particular issue.