SingleChildScrollView在任何地方都无法正常工作

Question

为了修复Bottom Overflow错误，我尝试使用SingleChildScrollView小部件。我尝试过将它包装到Column和Scaffold中，但是由于错误而导致了很多错误。

以下是导致错误的代码：

class SignUp extends StatefulWidget {

  @override
  _SignUpState createState() => _SignUpState();
}

class _SignUpState extends State<SignUp> {
  final formKey = GlobalKey<FormState>();

  final TextEditingController nameController = TextEditingController();
  final TextEditingController emailController = TextEditingController();
  final TextEditingController passwordController = TextEditingController();

  final nameNode = FocusNode();
  final emailNode = FocusNode();
  final passwordNode = FocusNode();

  bool isLoading = false;

  @override
  void initState() {
    super.initState();
  }

  @override
  void dispose() {
    nameController.dispose();
    emailController.dispose();
    passwordController.dispose();
    nameNode.dispose();
    emailNode.dispose();
    passwordNode.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    final isKeyboard = MediaQuery.of(context).viewInsets.bottom != 0;

    final appBar = AppBar(
      iconTheme: Theme.of(context).iconTheme,
      backgroundColor: Colors.transparent,
      leading: CustomBackButton(
        onPressed: () => print('Back Button Tapped'),
      ),
    );

    // ***** Checking for current Theme Mode *****
    var brightness = Theme.of(context).brightness;
    bool darkModeOn = brightness == Brightness.dark;

    return KeyboardDismisser(
      gestures: [
        GestureType.onTap,
        GestureType.onVerticalDragDown,
      ],
      child: Scaffold(
        resizeToAvoidBottomInset: false,
        appBar: isLoading ? null : appBar,
        body: SafeArea(
          child: Form(
            key: formKey,
            child: AutofillGroup(
              child: Center(
                child: SingleChildScrollView(
                  child: Padding(
                    padding: EdgeInsets.symmetric(horizontal: 5.w),
                    child: Column(
                      children: [
                        SizedBox(height: 2.h),
                        if (!isKeyboard) BuildHeader(title: 'Welcome Onboard'),
                        if (!isKeyboard) SizedBox(height: 2.5.h),
                        BuildNameField(nameController: nameController, nameNode: nameNode, emailNode: emailNode),
                        SizedBox(height: 2.5.h),
                        BuildEmailField(emailController: emailController, emailNode: emailNode, passwordNode: passwordNode),
                        SizedBox(height: 2.5.h),
                        BuildPasswordField(passwordController: passwordController, passwordNode: passwordNode),
                        SizedBox(height: 2.5.h),
                        buildEmailSignUpButton(),
                        SizedBox(height: 2.h),
                        BuildAccountExistsButton(),
                        Spacer(),
                        BuildDividerRow(darkModeOn: darkModeOn),
                        Spacer(),
                        buildGoogleSignUpButton(darkModeOn),
                        SizedBox(height: 3.h),
                        buildAppleSignUpButton(darkModeOn),
                        Spacer(),
                        BuildFooter(),
                      ],
                    ),
                  ),
                ),
              ),
            ),
          ),
        ),
      ),
    );
  }

我得到了以下错误，我不得不截断许多错误，因为它超过了允许的限制：

======== Exception caught by rendering library =====================================================
The following assertion was thrown during performLayout():
RenderFlex children have non-zero flex but incoming height constraints are unbounded.

When a column is in a parent that does not provide a finite height constraint, for example if it is in a vertical scrollable, it will try to shrink-wrap its children along the vertical axis. Setting a flex on a child (e.g. using Expanded) indicates that the child is to expand to fill the remaining space in the vertical direction.
These two directives are mutually exclusive. If a parent is to shrink-wrap its child, the child cannot simultaneously expand to fit its parent.

Consider setting mainAxisSize to MainAxisSize.min and using FlexFit.loose fits for the flexible children (using Flexible rather than Expanded). This will allow the flexible children to size themselves to less than the infinite remaining space they would otherwise be forced to take, and then will cause the RenderFlex to shrink-wrap the children rather than expanding to fit the maximum constraints provided by the parent.

If this message did not help you determine the problem, consider using debugDumpRenderTree():
  https://flutter.dev/debugging/#rendering-layer
  http://api.flutter.dev/flutter/rendering/debugDumpRenderTree.html
The affected RenderFlex is: RenderFlex#6b876 relayoutBoundary=up14 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
  needs compositing
  parentData: offset=Offset(20.6, 0.0) (can use size)
  constraints: BoxConstraints(0.0<=w<=370.3, 0.0<=h<=Infinity)
  size: MISSING
  direction: vertical
  mainAxisAlignment: start
  mainAxisSize: max
  crossAxisAlignment: center
  verticalDirection: down
...  child 1: RenderConstrainedBox#b86cb NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...    parentData: offset=Offset(0.0, 0.0); flex=null; fit=null
...    constraints: MISSING
...    size: MISSING
...    additionalConstraints: BoxConstraints(0.0<=w<=Infinity, h=13.7)
...  child 2: RenderPositionedBox#4f180 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...    parentData: offset=Offset(0.0, 0.0); flex=null; fit=null
...    constraints: MISSING
...    size: MISSING
...    alignment: Alignment.centerLeft
...    textDirection: ltr
...    widthFactor: expand
...    heightFactor: expand
...    child: RenderParagraph#eb54e NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...      parentData: offset=Offset(0.0, 0.0)
...      constraints: MISSING
...      size: MISSING
...      textAlign: start
...      textDirection: ltr
...      softWrap: wrapping at box width
...      overflow: clip
...      locale: en_US
...      maxLines: unlimited
...      text: TextSpan
...        debugLabel: (((englishLike display1 2014).merge(blackMountainView headline4)).copyWith).copyWith
...        inherit: false
...        color: Color(0x8a000000)
...        family: Roboto_700
...        familyFallback: Roboto
...        size: 27.4
...        weight: 700
...        baseline: alphabetic
...        decoration: TextDecoration.none
...        "Welcome Onboard"
...  child 3: RenderConstrainedBox#20957 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...    parentData: offset=Offset(0.0, 0.0); flex=null; fit=null
...    constraints: MISSING
...    size: MISSING
...    additionalConstraints: BoxConstraints(0.0<=w<=Infinity, h=17.1)
...  child 4: RenderConstrainedBox#dede6 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...    needs compositing
...    parentData: offset=Offset(0.0, 0.0); flex=null; fit=null
...    constraints: MISSING
...    size: MISSING
...    additionalConstraints: BoxConstraints(w=370.3, 0.0<=h<=Infinity)
...    child: RenderMouseRegion#22641 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...      needs compositing
...      parentData: <none>
...      constraints: MISSING
...      size: MISSING
...      listeners: enter, exit
...      cursor: SystemMouseCursor(text)
...      child: RenderIgnorePointer#749a8 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...        needs compositing
...        parentData: <none>
...        constraints: MISSING
...        size: MISSING
...        ignoring: false
...        ignoringSemantics: implicitly false
...        child: RenderSemanticsAnnotations#40667 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...          needs compositing
...          parentData: <none>
...          constraints: MISSING
...          size: MISSING
...  child 5: RenderConstrainedBox#67979 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...    parentData: offset=Offset(0.0, 0.0); flex=null; fit=null
...    constraints: MISSING
...    size: MISSING
...    additionalConstraints: BoxConstraints(0.0<=w<=Infinity, h=17.1)
...  child 6: RenderConstrainedBox#97d0d NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...    needs compositing
...    parentData: offset=Offset(0.0, 0.0); flex=null; fit=null
...    constraints: MISSING
...    size: MISSING
...    additionalConstraints: BoxConstraints(w=370.3, 0.0<=h<=Infinity)
...    child: RenderMouseRegion#7eeba NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...      needs compositing
...      parentData: <none>
...      constraints: MISSING
...      size: MISSING
...      listeners: enter, exit
...      cursor: SystemMouseCursor(text)
...      child: RenderIgnorePointer#01dea NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...        needs compositing
...        parentData: <none>
...        constraints: MISSING
...        size: MISSING
...        ignoring: false
...        ignoringSemantics: implicitly false
...        child: RenderSemanticsAnnotations#e03be NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...          needs compositing
...          parentData: <none>
...          constraints: MISSING
...          size: MISSING
...  child 7: RenderConstrainedBox#a5e4d NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...    parentData: offset=Offset(0.0, 0.0); flex=null; fit=null
...    constraints: MISSING
...    size: MISSING
...    additionalConstraints: BoxConstraints(0.0<=w<=Infinity, h=17.1)
...  child 8: RenderConstrainedBox#2f682 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...    needs compositing
...    parentData: offset=Offset(0.0, 0.0); flex=null; fit=null
...    constraints: MISSING
...    size: MISSING
...    additionalConstraints: BoxConstraints(w=370.3, 0.0<=h<=Infinity)
...    child: RenderMouseRegion#bcb98 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...      needs compositing
...      parentData: <none>
...      constraints: MISSING
...      size: MISSING
...      listeners: enter, exit
...      cursor: SystemMouseCursor(text)
...      child: RenderIgnorePointer#f66bd NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...        needs compositing
...        parentData: <none>
...        constraints: MISSING
...        size: MISSING
...        ignoring: false
...        ignoringSemantics: implicitly false
...        child: RenderSemanticsAnnotations#7e929 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...          needs compositing
...          parentData: <none>
...          constraints: MISSING
...          size: MISSING
...  child 9: RenderConstrainedBox#1714f NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...    parentData: offset=Offset(0.0, 0.0); flex=null; fit=null
...    constraints: MISSING
...    size: MISSING
...    additionalConstraints: BoxConstraints(0.0<=w<=Infinity, h=17.1)
...    child 1: RenderConstrainedBox#3498e NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...      parentData: offset=Offset(0.0, 0.0); flex=1; fit=FlexFit.tight
...      constraints: MISSING
...      size: MISSING
...      additionalConstraints: BoxConstraints(0.0<=w<=Infinity, h=0.0)
...      child: RenderPositionedBox#1b64a NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...        parentData: <none>
...        constraints: MISSING
...        size: MISSING
...        alignment: Alignment.center
...        textDirection: ltr
...        widthFactor: expand
...        heightFactor: expand
...        child: RenderPadding#eb6fd NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...          parentData: offset=Offset(0.0, 0.0)
...          constraints: MISSING
...          size: MISSING
...          padding: EdgeInsets.zero
...          textDirection: ltr
...    child 2: RenderConstrainedBox#eb389 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...      parentData: offset=Offset(0.0, 0.0); flex=null; fit=null
...      constraints: MISSING
...      size: MISSING
...      additionalConstraints: BoxConstraints(w=20.6, 0.0<=h<=Infinity)
...    child 3: RenderParagraph#93a61 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...      parentData: offset=Offset(0.0, 0.0); flex=null; fit=null
...      constraints: MISSING
...      size: MISSING
...      textAlign: start
...      textDirection: ltr
...      softWrap: wrapping at box width
...      overflow: clip
...      locale: en_US
...      maxLines: unlimited
...      text: TextSpan
...        debugLabel: ((englishLike body1 2014).merge(blackMountainView bodyText2)).merge(unknown)
...        inherit: false
...        color: Color(0xdd000000)
...        family: Roboto
...        size: 16.5
...        weight: 500
...        baseline: alphabetic
...        decoration: TextDecoration.none
...        "OR"
...    child 4: RenderConstrainedBox#50550 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...      parentData: offset=Offset(0.0, 0.0); flex=null; fit=null
...      constraints: MISSING
...      size: MISSING
...      additionalConstraints: BoxConstraints(w=20.6, 0.0<=h<=Infinity)
...    child 5: RenderConstrainedBox#2a7e1 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...      parentData: offset=Offset(0.0, 0.0); flex=1; fit=FlexFit.tight
...      constraints: MISSING
...      size: MISSING
...      additionalConstraints: BoxConstraints(0.0<=w<=Infinity, h=0.0)
...      child: RenderPositionedBox#0e343 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...        parentData: <none>
...        constraints: MISSING
...        size: MISSING
...        alignment: Alignment.center
...        textDirection: ltr
...        widthFactor: expand
...        heightFactor: expand
...        child: RenderPadding#afb85 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...          parentData: offset=Offset(0.0, 0.0)
...          constraints: MISSING
...          size: MISSING
...          padding: EdgeInsets.zero
...          textDirection: ltr
...  child 15: RenderConstrainedBox#451dd NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...    parentData: offset=Offset(0.0, 0.0); flex=1; fit=FlexFit.tight
...    constraints: MISSING
...    size: MISSING
...    additionalConstraints: BoxConstraints(w=0.0, h=0.0)
...    child 1: RenderParagraph#19d0c NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...      parentData: offset=Offset(0.0, 0.0); flex=null; fit=null
...      constraints: MISSING
...      size: MISSING
...      textAlign: center
...      textDirection: ltr
...      softWrap: wrapping at box width
...      overflow: clip
...      locale: en_US
...      maxLines: unlimited
...      text: TextSpan
...        debugLabel: ((englishLike body1 2014).merge(blackMountainView bodyText2)).merge(unknown)
...        inherit: false
...        color: Color(0xbf000000)
...        family: Roboto
...        size: 13.7
...        weight: 400
...        baseline: alphabetic
...        decoration: TextDecoration.none
...        "By using Netwersity you agree to it's"
...    child 2: RenderConstrainedBox#e36ee NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...      parentData: offset=Offset(0.0, 0.0); flex=null; fit=null
...      constraints: MISSING
...      size: MISSING
...      additionalConstraints: BoxConstraints(0.0<=w<=Infinity, h=3.4)
...    child 3: RenderFlex#ffd54 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...      parentData: offset=Offset(0.0, 0.0); flex=null; fit=null
...      constraints: MISSING
...      size: MISSING
...      direction: horizontal
...      mainAxisAlignment: center
...      mainAxisSize: max
...      crossAxisAlignment: center
...      textDirection: ltr
...      verticalDirection: down
...      child 1: RenderSemanticsGestureHandler#bd90f NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...        parentData: offset=Offset(0.0, 0.0); flex=null; fit=null
...        constraints: MISSING
...        size: MISSING
...        behavior: deferToChild
...        gestures: tap
...        child: RenderPointerListener#43b96 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...          parentData: <none>
...          constraints: MISSING
...          size: MISSING
...          behavior: deferToChild
...          listeners: down
...      child 2: RenderConstrainedBox#a0757 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...        parentData: offset=Offset(0.0, 0.0); flex=null; fit=null
...        constraints: MISSING
...        size: MISSING
...        additionalConstraints: BoxConstraints(w=4.1, 0.0<=h<=Infinity)
...      child 3: RenderParagraph#55e37 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...        parentData: offset=Offset(0.0, 0.0); flex=null; fit=null
...        constraints: MISSING
...        size: MISSING
...        textAlign: center
...        textDirection: ltr
...        softWrap: wrapping at box width
...        overflow: clip
...        locale: en_US
...        maxLines: unlimited
...        text: TextSpan
...          debugLabel: ((englishLike body1 2014).merge(blackMountainView bodyText2)).merge(unknown)
...          inherit: false
...          color: Color(0xbf000000)
...          family: Roboto
...          size: 13.7
...          weight: 400
...          baseline: alphabetic
...          decoration: TextDecoration.none
...          "and"
...      child 4: RenderConstrainedBox#fac5c NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...        parentData: offset=Offset(0.0, 0.0); flex=null; fit=null
...        constraints: MISSING
...        size: MISSING
...        additionalConstraints: BoxConstraints(w=4.1, 0.0<=h<=Infinity)
...      child 5: RenderSemanticsGestureHandler#52395 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...        parentData: offset=Offset(0.0, 0.0); flex=null; fit=null
...        constraints: MISSING
...        size: MISSING
...        behavior: deferToChild
...        gestures: tap
...        child: RenderPointerListener#92253 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...          parentData: <none>
...          constraints: MISSING
...          size: MISSING
...          behavior: deferToChild
...          listeners: down
...    child 4: RenderConstrainedBox#b1d09 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...      parentData: offset=Offset(0.0, 0.0); flex=null; fit=null
...      constraints: MISSING
...      size: MISSING
...      additionalConstraints: BoxConstraints(0.0<=w<=Infinity, h=13.7)
The creator information is set to: Column ← Padding ← _SingleChildViewport ← IgnorePointer-[GlobalKey#13af8] ← Semantics ← Listener ← _GestureSemantics ← RawGestureDetector-[LabeledGlobalKey<RawGestureDetectorState>#94304] ← Listener ← _ScrollableScope ← _ScrollSemantics-[GlobalKey#6bebf] ← RepaintBoundary ← ⋯
The nearest ancestor providing an unbounded width constraint is: _RenderSingleChildViewport#cf013 relayoutBoundary=up12 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...  needs compositing
...  parentData: <none> (can use size)
...  constraints: BoxConstraints(0.0<=w<=411.4, 0.0<=h<=603.4)
...  size: MISSING

See also: https://flutter.dev/layout/

If none of the above helps enough to fix this problem, please don't hesitate to file a bug:
  https://github.com/flutter/flutter/issues/new?template=2_bug.md
The relevant error-causing widget was: 
  Column file:///Users/sas/Projects/Development/App/Flutter/my_app/lib/screens/sign_up.dart:81:28
When the exception was thrown, this was the stack: 
#0      RenderFlex.performLayout.<anonymous closure> (package:flutter/src/rendering/flex.dart:926:9)
#1      RenderFlex.performLayout (package:flutter/src/rendering/flex.dart:929:6)
#2      RenderObject.layout (package:flutter/src/rendering/object.dart:1779:7)
#3      RenderPadding.performLayout (package:flutter/src/rendering/shifted_box.dart:233:12)
#4      RenderObject.layout (package:flutter/src/rendering/object.dart:1779:7)
...
The following RenderObject was being processed when the exception was fired: RenderFlex#6b876 relayoutBoundary=up14 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...  needs compositing
...  parentData: offset=Offset(20.6, 0.0) (can use size)
...  constraints: BoxConstraints(0.0<=w<=370.3, 0.0<=h<=Infinity)
...  size: MISSING
...  direction: vertical
...  mainAxisAlignment: start
...  mainAxisSize: max
...  crossAxisAlignment: center
...  verticalDirection: down
RenderObject: RenderFlex#6b876 relayoutBoundary=up14 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
  needs compositing
  parentData: offset=Offset(20.6, 0.0) (can use size)
  constraints: BoxConstraints(0.0<=w<=370.3, 0.0<=h<=Infinity)
  size: MISSING
  direction: vertical
  mainAxisAlignment: start
  mainAxisSize: max
  crossAxisAlignment: center
  verticalDirection: down
...  child 1: RenderConstrainedBox#b86cb NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...    parentData: offset=Offset(0.0, 0.0); flex=null; fit=null
...    constraints: MISSING
...    size: MISSING
...    additionalConstraints: BoxConstraints(0.0<=w<=Infinity, h=13.7)
...  child 2: RenderPositionedBox#4f180 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...    parentData: offset=Offset(0.0, 0.0); flex=null; fit=null
...    constraints: MISSING
...    size: MISSING
...    alignment: Alignment.centerLeft
...    textDirection: ltr
...    widthFactor: expand
...    heightFactor: expand
...    child: RenderParagraph#eb54e NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...      parentData: offset=Offset(0.0, 0.0)
...      constraints: MISSING
...      size: MISSING
...      textAlign: start
...      textDirection: ltr
...      softWrap: wrapping at box width
...      overflow: clip
...      locale: en_US
...      maxLines: unlimited
...      text: TextSpan
...        debugLabel: (((englishLike display1 2014).merge(blackMountainView headline4)).copyWith).copyWith
...        inherit: false
...        color: Color(0x8a000000)
...        family: Roboto_700
...        familyFallback: Roboto
...        size: 27.4
...        weight: 700
...        baseline: alphabetic
...        decoration: TextDecoration.none
...        "Welcome Onboard"
...  child 3: RenderConstrainedBox#20957 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...    parentData: offset=Offset(0.0, 0.0); flex=null; fit=null
...    constraints: MISSING
...    size: MISSING
...    additionalConstraints: BoxConstraints(0.0<=w<=Infinity, h=17.1)
...  child 4: RenderConstrainedBox#dede6 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...    needs compositing
...    parentData: offset=Offset(0.0, 0.0); flex=null; fit=null
...    constraints: MISSING
...    size: MISSING
...    additionalConstraints: BoxConstraints(w=370.3, 0.0<=h<=Infinity)
...    child: RenderMouseRegion#22641 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...      needs compositing
...      parentData: <none>
...      constraints: MISSING
...      size: MISSING
...      listeners: enter, exit
...      cursor: SystemMouseCursor(text)
...      child: RenderIgnorePointer#749a8 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...        needs compositing
...        parentData: <none>
...        constraints: MISSING
...        size: MISSING
...        ignoring: false
...        ignoringSemantics: implicitly false
...        child: RenderSemanticsAnnotations#40667 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...          needs compositing
...          parentData: <none>
...          constraints: MISSING
...          size: MISSING
...  child 5: RenderConstrainedBox#67979 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
...    parentData: offset=Offset(0.0, 0.0); flex=null; fit=null
...    constraints: MISSING
...    size: MISSING
...    additionalConstraints: BoxConstraints(0.0<=w<=Infinity, h=17.1)

======== Exception caught by rendering library =====================================================
RenderBox was not laid out: RenderPadding#79c8b relayoutBoundary=up13 NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
'package:flutter/src/rendering/box.dart':
Failed assertion: line 1930 pos 12: 'hasSize'
The relevant error-causing widget was: 
  SingleChildScrollView file:///Users/sas/Projects/Development/App/Flutter/my_app/lib/screens/sign_up.dart:78:24
====================================================================================================
.
.
.
======== Exception caught by rendering library =====================================================
RenderBox was not laid out: _RenderSingleChildViewport#cf013 relayoutBoundary=up12 NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
'package:flutter/src/rendering/box.dart':
Failed assertion: line 1930 pos 12: 'hasSize'
The relevant error-causing widget was: 
  SingleChildScrollView file:///Users/sas/Projects/Development/App/Flutter/my_app/lib/screens/sign_up.dart:78:24
====================================================================================================

Answer 1

代码的问题是，Column试图收缩包装并适合SingleChildScrollView。但是，您的列小部件可能没有给出异常的有限大小。也许将Column放在Expanded小部件中可以考虑溢出(无限长度)，并使列可滚动。

child: SingleChildScrollView(
  child: Padding(
    padding: EdgeInsets.symmetric(horizontal: 5.w),
    child: Expanded(  // This widget is added here
      child: Column(...),
    ),
  ),
),

尝试上面的代码很可能会解决您的问题。

编辑：

上面的解决方案可能不能解决问题。

下面的链接是类似问题的参考，OP能够解决这个问题，并为同样的问题添加了答案。

How to use Expanded in SingleChildScrollView?一个类似于相同情况的答案。如果你也检查那里的话可能会很有用。

Answer 2

最后，从这个问题How to use Expanded in SingleChildScrollView?中找到了这个问题的解决方案

这是一个对我有效的解决方案：

LayoutBuilder(
  builder: (context, constraint) {
    return SingleChildScrollView(
      child: ConstrainedBox(
        constraints: BoxConstraints(minHeight: constraint.maxHeight),
        child: IntrinsicHeight(
          child: Column(
            children: <Widget>[
              Text("Header"),
              Expanded(
                child: Container(
                  color: Colors.red,
                ),
              ),
              Text("Footer"),
            ],
          ),
        ),
      ),
    );
  },
)

Answer 3

我也发现了同样的问题。

解决方案：

替换

SingleChildScrollView(
  physics: BouncingScrollPhysics()
                  child: Padding(
                    padding: EdgeInsets.symmetric(horizontal: 5.w),
                    child: ListView(
                      physics: NeverScrollableScrollPhysics(),

使用

SingleChildScrollView(
              child: Padding(
                padding: EdgeInsets.symmetric(horizontal: 5.w),
                child: Column(

它肯定会起作用。