Running into the old Error 4020. There was an error during the IIS configuration process. issue on one of our client machines. Is there an IIS.dll that does the extra logging available for AI 11.1?
In order to get more details about what happens can you download the attached debug DLL, replace the original one from the install folder of Advanced Installer 11.1 (e.g. C:\Program Files (x86)\Caphyon\Advanced Installer 11.1\custact\x86) on your machine and rebuild the package?
Just replace the original "iis.dll" from the install folder of Advanced Installer with this one, then restart the application and rebuild the package. This DLL should create a debug log (at install time) on the root of the OS partition (e.g. C:\AI_IIS.log), which can give us more details about the problem.
I looked over the log file that you sent, but I am still not sure why the problem appear. Can you please send us the AIP file to support at advancedinstaller dot com, so we can take a look of it? Also, can you please go in the "Windows Event Viewer" and see if there are any IIS errors?