I have the same problem, link: https://stackoverflow.com/questions/49770654/uidatepicker-nsinternalinconsistencyexception-unexpected-number-of-calendar-uni The first answer cannot fix this bug. Help, please Crash report below: Fatal Exception: NSInternalInconsistencyException unexpected number of calendar units: 4 for format: EEE ├'day': d┤ HH.mm (expecting at least 5 elements) Fatal Exception: NSInternalInconsistencyException 0 CoreFoundation 0x184bb5d04 __exceptionPreprocess 1 libobjc.A.dylib 0x183e04528 objc_exception_throw 2 CoreFoundation 0x184bb5bd8 +[NSException raise:format:] 3 Foundation 0x185545c24 -[NSAssertionHandler handleFailureInMethod:object:file:lineNumber:description:] 4 UIKit 0x18eab9b38 -[_UIDatePickerMode_DateAndTime elements] 5 UIKit 0x18eab3898 -[_UIDatePickerMode displayedCalendarUnits] 6 UIKit 0x18eab98f8 -[_UIDatePickerMode_DateAndTime displayedCalendarUnits] 7 UIKit 0x18eaa8448 -[_UIDatePickerView _setMode:] 8 UIKit 0x18eaa8694 -[_UIDatePickerView setDatePickerMode:] 9 UIKit 0x18e55ac68 -[UIDatePicker initWithCoder:] 10 UIKit 0x18e727160 UINibDecoderDecodeObjectForValue 11 UIKit 0x18e726e98 -[UINibDecoder decodeObjectForKey:] 12 UIKit 0x18e57c0cc -[UIRuntimeConnection initWithCoder:] 13 UIKit 0x18e727160 UINibDecoderDecodeObjectForValue 14 UIKit 0x18e7272d8 UINibDecoderDecodeObjectForValue 15 UIKit 0x18e726e98 -[UINibDecoder decodeObjectForKey:] 16 UIKit 0x18e57b40c -[UINib instantiateWithOwner:options:] 17 UIKit 0x18e35b17c -[UIViewController _loadViewFromNibNamed:bundle:] 18 UIKit 0x18e10aee4 -[UIViewController loadView] 19 UIKit 0x18dfecba4 -[UIViewController loadViewIfRequired] 20 UIKit 0x18dfecad4 -[UIViewController view] 21 UIKit 0x18e171680 -[UINavigationController _startCustomTransition:] 22 UIKit 0x18e0932c8 -[UINavigationController _startDeferredTransitionIfNeeded:] 23 UIKit 0x18e092f0c -[UINavigationController __viewWillLayoutSubviews] 24 UIKit 0x18e092e0c -[UILayoutContainerView layoutSubviews] 25 UIKit 0x1a3a651b8 -[UILayoutContainerViewAccessibility layoutSubviews] 26 UIKit 0x18dfea2f8 -[UIView(CALayerDelegate) layoutSublayersOfLayer:] 27 QuartzCore 0x188ba3ec8 -[CALayer layoutSublayers] 28 QuartzCore 0x188ba7fa8 CA::Layer::layout_if_needed(CA::Transaction*) 29 QuartzCore 0x188b16a98 CA::Context::commit_transaction(CA::Transaction*) 30 QuartzCore 0x188b3ceb4 CA::Transaction::commit() 31 QuartzCore 0x188b3dcf4 CA::Transaction::observer_callback(__CFRunLoopObserver*, unsigned long, void*) 32 CoreFoundation 0x184b5d848 CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION 33 CoreFoundation 0x184b5b200 __CFRunLoopDoObservers 34 CoreFoundation 0x184b5b7bc __CFRunLoopRun 35 CoreFoundation 0x184a7bfb8 CFRunLoopRunSpecific 36 GraphicsServices 0x186913f84 GSEventRunModal 37 UIKit 0x18e0502e8 UIApplicationMain 38 AwesomeApp 0x100da4924 main (AppDelegate.swift:18) 39 libdyld.dylib 0x18459e56c start