appium: Ran tests on a real device and got [XCUITest] Error checking install status: spawn EACCES

iOS 10.0.2 (real device) / XCode 8

When running Appium 1.6 beta 3 I got the following error trace. Anyone has a clue? Thanks!

[XCUITest] Setting up real device
[debug] [XCUITest] Error checking install status: spawn EACCES
[debug] [XCUITest] App is not installed. Will try to install.
[debug] [XCUITest] Error : spawn EACCES
[XCUITest] Error: could not install app spawn EACCES
    at IOSDeploy.install$ (lib/ios-deploy.js:37:13)
    at tryCatch (/Users/someone/someone/src/appium/node_modules/babel-runtime/regenerator/runtime.js:67:40)
    at GeneratorFunctionPrototype.invoke [as _invoke] (/Users/someone/someone/src/appium/node_modules/babel-runtime/regenerator/runtime.js:315:22)
    at GeneratorFunctionPrototype.prototype.(anonymous function) [as throw] (/Users/someone/someone/src/appium/node_modules/babel-runtime/regenerator/runtime.js:100:21)
    at GeneratorFunctionPrototype.invoke (/Users/someone/someone/src/appium/node_modules/babel-runtime/regenerator/runtime.js:136:37)
 Error: could not install app spawn EACCES
    at IOSDeploy.install$ (lib/ios-deploy.js:37:13)
    at tryCatch (/Users/someone/someone/src/appium/node_modules/babel-runtime/regenerator/runtime.js:67:40)
    at GeneratorFunctionPrototype.invoke [as _invoke] (/Users/someone/someone/src/appium/node_modules/babel-runtime/regenerator/runtime.js:315:22)
    at GeneratorFunctionPrototype.prototype.(anonymous function) [as throw] (/Users/someone/someone/src/appium/node_modules/babel-runtime/regenerator/runtime.js:100:21)
    at GeneratorFunctionPrototype.invoke (/Users/someone/someone/src/appium/node_modules/babel-runtime/regenerator/runtime.js:136:37)
[debug] [XCUITest] Running ios real device reset flow
[debug] [XCUITest] Resetting simulator
[debug] [iOSLog] Stopping iOS log capture
[MJSONWP] Encountered internal error running command: Error: could not install app spawn EACCES
    at IOSDeploy.install$ (lib/ios-deploy.js:37:13)
    at tryCatch (/Users/someone/someone/src/appium/node_modules/babel-runtime/regenerator/runtime.js:67:40)
    at GeneratorFunctionPrototype.invoke [as _invoke] (/Users/someone/someone/src/appium/node_modules/babel-runtime/regenerator/runtime.js:315:22)
    at GeneratorFunctionPrototype.prototype.(anonymous function) [as throw] (/Users/someone/someone/src/appium/node_modules/babel-runtime/regenerator/runtime.js:100:21)
    at GeneratorFunctionPrototype.invoke (/Users/someone/someone/src/appium/node_modules/babel-runtime/regenerator/runtime.js:136:37)
[HTTP] <-- POST /wd/hub/session 500 1501 ms - 171