I’m testing the latest build (10/7/2017) from your download page.
I had a v1.5 build that fixed issues with the proxy server. It took ~30 secs from start to usable. Before that I could only run the v1.3 release.
This new build starts in about 9 seconds showing the splash screen and then it crashes with a Fatal Error: The application server could not be contacted.
There is nothing in the Event Viewer logs and the pgAdmin log is empty in C:\Users\username\AppData\Roaming\pgAdmin
The registry key in HKEY_CURRENT_USER\Software\pgadmin\pgadmin4 is blank with a value not set.