When I tried to build and run, Xcode said my device was locked. I looked at my iPhone, and it\'s not locked at all. How do I fix this?
I recently ran into this issue with XCode 8 just after updating my device from iOS 9 to 10. The exact error I received was:Development cannot be enabled while your device is locked. Please unlock your device and reattach.
I received this error even when my phone was unlocked, and after unplugging and re-plugging in the device.
As is mentioned in several answers, the device is locked
message is actually referring to the device not trusting the MacBook. In my case, I think my phone defaulted to not trusting my computer after updating to iOS 10. Here are the steps that worked for me to reset the settings (this is the same process that is mentioned in the Apple support page in tehprofessors' answer):
Settings > General > Reset
, then tap Reset Location & Privacy
device locked
error should disappear.