Why does running Fiddler fix Edge browser's issue with VirtualBox / Vagrant?

[daniel...@inspireemail.co.uk]

Hello group,

Microsoft Edge browser has a know problem where it doesn't like to connect to websites running under local VirtualBoxes (https://answers.microsoft.com/en-us/insider/forum/insider_internet-insider_spartan/edge-not-displaying-sites-hosted-in-vagrant/41a34b7b-7d79-4866-acf3-739a9efd1680 and https://www.hanselman.com/blog/FixedMicrosoftEdgeCantSeeOrOpenVirtualBoxhostedLocalWebSites.aspx). I haven't been able to resolve this issuse myself.

But I have seen from https://stackoverflow.com/questions/38333641/microsoft-edge-wont-load-local-nginx-website-in-vagrant-vm that one solution is to simply have Fiddler running. Wow, this really works!

This is lovely, but *why* does this fix things? How is it working? Is it fixing this issue on purpose or as a side-effect?

Curiously yours,

Daniel

[EricLaw]

The most likely cause is that the sites are deemed "Private Network" by the firewall, but are being asked to load in an Internet-Zone AppContainer. You can usually fix these by changing the firewall's configuration or by putting the sites' hostnames into the Internet Control Panel's "Trusted Sites Zone."

See the Private Network resources section of https://blogs.msdn.microsoft.com/ieinternals/2012/03/23/understanding-enhanced-protected-mode/