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I'm trying to add a DropdownButton to my application but it is not rendered, the message "Bottom overflowed by infinity pixels" appears, I tried putting it in a SizeBox, Paddign, ConstrainedBox, Row, but nothing works, see the code:

@override
 Widget build(BuildContext context) 
 return new Scaffold(
 appBar: new AppBar(
 title: new Text(
 'Configurações',
 style: TextStyle(color: Colors.white),
 ),
 actions: <Widget>[new IconButton(icon: new Icon(Icons.check), onPressed: _salvar)],
 ),
 body: new Container(
 color: Colors.orange[50],
 padding: EdgeInsets.all(16.0),
 child: new Form(
 child: new Column(
 children: <Widget>[
 new TextFormField(
 decoration: new InputDecoration(labelText: 'Código da empresa'),
 //border: OutlineInputBorder()
 autofocus: true,
 controller: _edCodigoEmpresa,
 keyboardType: TextInputType.numberWithOptions(),
 ),
 new TextFormField(
 decoration: new InputDecoration(labelText: 'Código do funcionário'),
 controller: _edCodigoFuncionario,
 keyboardType: TextInputType.numberWithOptions(),
 ),
 new DropdownButton(
 value: _baseSelecionada,
 items: _basesCliente,
 onChanged: _baseChange,
 )
 ],
 ),
 ),
 ),
 );
 
}

But when you run the app, the following error message appears:

I/flutter (16684): ══╡ EXCEPTION CAUGHT BY RENDERING LIBRARY ╞═════════════════════════════════════════════════════════
I/flutter (16684): The following assertion was thrown during performLayout():
I/flutter (16684): RenderIndexedStack object was given an infinite size during layout.
I/flutter (16684): This probably means that it is a render object that tries to be as big as possible, but it was put
I/flutter (16684): inside another render object that allows its children to pick their own size.
I/flutter (16684): The nearest ancestor providing an unbounded width constraint is:
I/flutter (16684): RenderFlex#b60e0 relayoutBoundary=up9 NEEDS-LAYOUT NEEDS-PAINT
I/flutter (16684): creator: Row ← Padding ← Container ← DefaultTextStyle ← Stack ← Listener ← _GestureSemantics ←
I/flutter (16684): RawGestureDetector ← GestureDetector ← Semantics ← DropdownButton<String> ← Column ← ⋯
I/flutter (16684): parentData: offset=Offset(0.0, 0.0) (can use size)
I/flutter (16684): constraints: BoxConstraints(0.0<=w<=328.0, 0.0<=h<=Infinity)
I/flutter (16684): size: Size(328.0, Infinity)
I/flutter (16684): direction: horizontal
I/flutter (16684): mainAxisAlignment: spaceBetween
I/flutter (16684): mainAxisSize: min
I/flutter (16684): crossAxisAlignment: center
I/flutter (16684): textDirection: ltr
I/flutter (16684): verticalDirection: down
I/flutter (16684): The nearest ancestor providing an unbounded height constraint is:
I/flutter (16684): RenderFlex#783bc relayoutBoundary=up3 NEEDS-LAYOUT NEEDS-PAINT OVERFLOWING
I/flutter (16684): creator: Column ← _FormScope ← WillPopScope ← Form ← Padding ← DecoratedBox ← Container ←
I/flutter (16684): MediaQuery ← LayoutId-[<_ScaffoldSlot.body>] ← CustomMultiChildLayout ← AnimatedBuilder ←
I/flutter (16684): DefaultTextStyle ← ⋯
I/flutter (16684): parentData: offset=Offset(16.0, 16.0) (can use size)
I/flutter (16684): constraints: BoxConstraints(0.0<=w<=328.0, 0.0<=h<=528.0)
I/flutter (16684): size: Size(328.0, 528.0)
I/flutter (16684): direction: vertical
I/flutter (16684): mainAxisAlignment: start
I/flutter (16684): mainAxisSize: max
I/flutter (16684): crossAxisAlignment: center
I/flutter (16684): verticalDirection: down
I/flutter (16684): The constraints that applied to the RenderIndexedStack were:
I/flutter (16684): BoxConstraints(unconstrained)
I/flutter (16684): The exact size it was given was:
I/flutter (16684): Size(Infinity, Infinity)
I/flutter (16684): See https://flutter.io/layout/ for more information.
I/flutter (16684): 
I/flutter (16684): When the exception was thrown, this was the stack:
I/flutter (16684): #0 RenderBox.debugAssertDoesMeetConstraints.<anonymous closure> (package:flutter/src/rendering/box.dart:1749:9)
I/flutter (16684): #1 RenderBox.debugAssertDoesMeetConstraints (package:flutter/src/rendering/box.dart:1823:6)
I/flutter (16684): #2 RenderBox.size=.<anonymous closure> (package:flutter/src/rendering/box.dart:1543:17)
I/flutter (16684): #3 RenderBox.size= (package:flutter/src/rendering/box.dart:1543:65)
I/flutter (16684): #4 RenderStack.performLayout (package:flutter/src/rendering/stack.dart:480:7)
I/flutter (16684): #5 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (16684): #6 RenderFlex.performLayout (package:flutter/src/rendering/flex.dart:738:15)
I/flutter (16684): #7 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (16684): #8 RenderPadding.performLayout (package:flutter/src/rendering/shifted_box.dart:199:11)
I/flutter (16684): #9 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (16684): #10 RenderStack.performLayout (package:flutter/src/rendering/stack.dart:510:15)
I/flutter (16684): #11 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (16684): #12 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)
I/flutter (16684): #13 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (16684): #14 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)
I/flutter (16684): #15 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (16684): #16 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)
I/flutter (16684): #17 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (16684): #18 RenderFlex.performLayout (package:flutter/src/rendering/flex.dart:738:15)
I/flutter (16684): #19 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (16684): #20 RenderPadding.performLayout (package:flutter/src/rendering/shifted_box.dart:199:11)
I/flutter (16684): #21 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (16684): #22 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)
I/flutter (16684): #23 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (16684): #24 MultiChildLayoutDelegate.layoutChild (package:flutter/src/rendering/custom_layout.dart:141:11)
I/flutter (16684): #25 _ScaffoldLayout.performLayout (package:flutter/src/material/scaffold.dart:339:7)
I/flutter (16684): #26 MultiChildLayoutDelegate._callPerformLayout (package:flutter/src/rendering/custom_layout.dart:211:7)
I/flutter (16684): #27 RenderCustomMultiChildLayoutBox.performLayout (package:flutter/src/rendering/custom_layout.dart:355:14)
I/flutter (16684): #28 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (16684): #29 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)
I/flutter (16684): #30 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (16684): #31 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)
I/flutter (16684): #32 _RenderCustomClip.performLayout (package:flutter/src/rendering/proxy_box.dart:1188:11)
I/flutter (16684): #33 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (16684): #34 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)
I/flutter (16684): #35 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (16684): #36 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)
I/flutter (16684): #37 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (16684): #38 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)
I/flutter (16684): #39 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (16684): #40 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)
I/flutter (16684): #41 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (16684): #42 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)
I/flutter (16684): #43 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (16684): #44 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)
I/flutter (16684): #45 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (16684): #46 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)
I/flutter (16684): #47 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (16684): #48 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)
I/flutter (16684): #49 RenderOffstage.performLayout (package:flutter/src/rendering/proxy_box.dart:2880:13)
I/flutter (16684): #50 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (16684): #51 RenderStack.performLayout (package:flutter/src/rendering/stack.dart:510:15)
I/flutter (16684): #52 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (16684): #53 __RenderTheatre&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)
I/flutter (16684): #54 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (16684): #55 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)
I/flutter (16684): #56 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (16684): #57 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)
I/flutter (16684): #58 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (16684): #59 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)
I/flutter (16684): #60 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (16684): #61 _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)
I/flutter (16684): #62 RenderObject.layout (package:flutter/src/rendering/object.dart:1632:7)
I/flutter (16684): #63 RenderView.performLayout (package:flutter/src/rendering/view.dart:147:13)
I/flutter (16684): #64 RenderObject._layoutWithoutResize (package:flutter/src/rendering/object.dart:1507:7)
I/flutter (16684): #65 PipelineOwner.flushLayout (package:flutter/src/rendering/object.dart:766:18)
I/flutter (16684): #66 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding&PaintingBinding&SemanticsBinding&RendererBinding.drawFrame (package:flutter/src/rendering/binding.dart:281:19)
I/flutter (16684): #67 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding&PaintingBinding&SemanticsBinding&RendererBinding&WidgetsBinding.drawFrame (package:flutter/src/widgets/binding.dart:674:13)
I/flutter (16684): #68 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding&PaintingBinding&SemanticsBinding&RendererBinding._handlePersistentFrameCallback (package:flutter/src/rendering/binding.dart:219:5)
I/flutter (16684): #69 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:990:15)
I/flutter (16684): #70 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:930:9)
I/flutter (16684): #71 _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding.scheduleWarmUpFrame.<anonymous closure> (package:flutter/src/scheduler/binding.dart:751:7)
I/flutter (16684): #73 _Timer._runTimers (dart:isolate/runtime/libtimer_impl.dart:382:19)
I/flutter (16684): #74 _Timer._handleMessage (dart:isolate/runtime/libtimer_impl.dart:416:5)
I/flutter (16684): #75 _RawReceivePortImpl._handleMessage (dart:isolate/runtime/libisolate_patch.dart:171:12)
I/flutter (16684): (elided one frame from package dart:async)
I/flutter (16684): 
I/flutter (16684): The following RenderObject was being processed when the exception was fired:
I/flutter (16684): RenderIndexedStack#b8a3e relayoutBoundary=up10 NEEDS-LAYOUT NEEDS-PAINT
I/flutter (16684): creator: IndexedStack ← Row ← Padding ← Container ← DefaultTextStyle ← Stack ← Listener ←
I/flutter (16684): _GestureSemantics ← RawGestureDetector ← GestureDetector ← Semantics ← DropdownButton<String> ← ⋯
I/flutter (16684): parentData: offset=Offset(0.0, 0.0); flex=null; fit=null (can use size)
I/flutter (16684): constraints: BoxConstraints(unconstrained)
I/flutter (16684): size: Size(Infinity, Infinity)
I/flutter (16684): alignment: AlignmentDirectional.centerStart
I/flutter (16684): textDirection: ltr
I/flutter (16684): fit: loose
I/flutter (16684): overflow: clip
I/flutter (16684): index: null
I/flutter (16684): This RenderObject has no descendants.
I/flutter (16684): ════════════════════════════════════════════════════════════════════════════════════════════════════
I/flutter (16684): Another exception was thrown: RenderFlex object was given an infinite size during layout.
I/flutter (16684): Another exception was thrown: RenderPadding object was given an infinite size during layout.
I/flutter (16684): Another exception was thrown: RenderStack object was given an infinite size during layout.
I/flutter (16684): Another exception was thrown: RenderPointerListener object was given an infinite size during layout.
I/flutter (16684): Another exception was thrown: RenderSemanticsGestureHandler object was given an infinite size during layout.
I/flutter (16684): Another exception was thrown: RenderSemanticsAnnotations object was given an infinite size during layout.
I/flutter (16684): Another exception was thrown: NoSuchMethodError: The method '<=' was called on null.
I/flutter (16684): Another exception was thrown: A RenderFlex overflowed by Infinity pixels on the bottom.

can anybody help me?

I used a ConstrainedBox to set a maxHeight but then it still overflowed to the right by infinity. I had to set isExpanded: true and then wrap the ConstrainedBox inside of Row -> Expanded.

Column(
 children: <Widget>[
 Row(
 children: <Widget>[
 Expanded(
 child: ConstrainedBox(
 constraints: const BoxConstraints(maxHeight: 48.0),
 child: DropdownButton<String>(
 isExpanded: true, ...
 )
 )
 )
 ]
 )
 ]
)

That happens because the view can’t expand to fit its content when you toggle the dropdown.

Either you constrain it to use only available space (i.e., wrapping children widgets of Column in Flexible widgets such as Expanded) or make your view scrollable by, for example, wrapping your body Container in a SingleChildScrollView widget.

Scaffold(
 body: SingleChildScrollView(
 child: Container(
 ...