Hello,
If my installer is unable to download any of its prerequisites, I get an "Error 1001" dialog and the installer aborts with "Setup ended prematurely because of an error." This appears to be the case since AI 13.5, and is still an issue with AI 14.0.1. My prerequisite is set to "Continue with main installation even if prerequisite is not installed", but the error still occurs. I also made sure "Show error if the prerequisite is not downloaded correctly" was not checked.
I've attached a sample *.aip project to reproduce the issue.
Thanks,
Brandon