Install failed E-1223
specs:
win 10, good computer (32 ram, GF Titan, > 1Tb free space)
I already installed and working 4.9 and 4.10) vs 2015 community and they work for blueprints and for C++.
Extra info, it downloaded all the engine, after verify step is when it shows the error.
Exact same problem here,
same one I already hit with 4.10.0 with Visual Studio 2015 Update 1,
then with 4.10.1 with Visual Studio 2015 (not updated)…
Many people report same kind of issues (search for the error code). Here is a workaround :
For this time I did not bother to try to solve it, I uninstalled the preview immediately 
Best regards
welll I didnt need to do anything special, aparently after 2 or 3 times that didnt work, after return from work and start my PC, did the continue step… and it verified and request me to install prerequisites and I did acept and it worked.
To me it seem the other 2 or 3 times it didnt run the prerequisites… indeed an odd error.
4.11preview4 worked for me after I uninstalled the “UE4 Prerequisites” or something like that. Funny thing was after 4.11preview4 installed, there was no prerequisites package reinstalled.
The cause (or primary cause) of the E-1223 error is believed to be due to users being away from their computer when the installation finishes, and the failure occurs because Windows UAC times out while waiting for authorization. The obvious workaround is to be present when the download and installation finishes. Epic is currently looking into ways to resolve this matter.
This worked for me, after 2 o 3 times that work. I didnt do anything else.
Regards.