Device not specified or the combination of device, version, and operating system you may have entered (to use in your tests) is not supported.
Use the list of supported devices/versions to make sure your selections are valid.
For Appium (Set the device and os_version capabilities)
"device": "Samsung Galaxy S8 Plus" "os_version": "9.0"
For Espresso/XCUITest/Flutter (Set the devices parameters)
"devices": ["Samsung Galaxy S8-7.0", "Google Nexus 6-6.0"]
Checkout the following documentations to ensure you are passing device related capabilities properly: