Samsung Galaxy S4 "Prevention Information" USB OTG I am trying to connect things to my S4 with a USB OTG cable. Standard devices such as mass storage, keyboard and mouse all work fine. My problem seems to be with vendor class devices.

I connected an FTDI USB to UART bridge (TTL-232R-3V3) to a USB OTG cable and installed the FTDI app. I plugged in the OTG cable and the phone reccognised the FTDI chip, launched the app, waited a few seconds and then closed the app again.

I got the message:

"Prevention Information, An application has been forced to stop for an unauthorized attempt to access system in your device". (Including the grammatical error)

I have the same problem with my Arduino Uno using the ArduinoDriod app.

I tried both devices on a friend's Huawei p6 and they both worked fine. From what I can tell, this issue is specific to the S4 and seems to be related to the recent update to Samsung Knox.

Does anyone know of a work around that doesn't involve rooting the device?

I am still in the 14 day trial period of the phone, so I could swap it for a different one. How do I tell if the Galaxy Note 3 or the LG G2 will have the same problem?
I did also read about this. KNOX seems to be blocking the communication to USB devices in some cases.

The Google Nexus 5 (LG) is also available now. Its pretty cheap for the features it offers. You should take a look at it before you swap you device. There is also a ROOT available for the SGS4 but it would break your warranty ofcourse:

This is where i read it

more about the root. only use the one from the xda-developers forum!