Hello,
I try to install a .ipsw of iOS 13 MG with macOS Catalina 10.15 Beta (19A558d) on an iPhone 7 under iOS 13.1 beta 3 (17a5837a).
To do it, I select my iPhone in finder and press "Restore iPhone...". Then I have an error "There was a problem downloading the software for the iPhone "iPhone 7". The requested resource was not found".
The phone is also ejected from finder but it happens also when I don't press the restore button.
You can see the demo video here : https://www.youtube.com/watch?v=wku8Pk0pN6c&feature=youtu.be
Someone is aware about this bug ?