After multiple errors on Windows 10 (plugin not working in Chrome but apparently working with Mozilla, but at the end it didn't ...) I switched back to Windows 7 Pro.
These are my first errors and successful test:
1)Installed Windows 7 Pro 2)Installed Chrome and Mozilla 3)Installed Arduino Create Agent 4)Connecting an Arduino Mega board to USB
5)Opened Arduino Create webpage on both Chrome and Mozilla and because Arduino board is not recognized the plugin is not working on either browser!
6)Disconnecting Arduino Mega from USB 7)Installed Arduino IDE 1.6.7 (with drivers) 8)Connecting an Arduino Mega board to USB
9)Now opened Arduino Create webpage on both Chrome and Mozilla (still "No plugin connection error") 9)Connecting Arduino Mega board and ONLY on Mozilla the plugin detected the board and it's working. I upload simple "Blink" sketch to board and it works!
I attach a combined picture of the two browser at the same moment, one working and one not: roboticage_error_plugin_Chrome_vs_Mozilla.png
System: ASUS F3Sg (Intel Core2Duo 2.4GHz, 4GB RAM, GeForce9300M) System OS: Windows 7 Pro Browsers: Mozilla firefox 43.0.2 (tested and plugin works) Google chrome Version 47.0.2526.106m (tested and plugin fails to connect)