Fix crash when errorBuilder is used with decoration containing errorText by 04cb · Pull Request #183384 · flutter/flutter

04cb · 2026-03-09T00:43:15Z

Fixes #183378. When using errorBuilder alongside a decoration that has errorText, both error and errorText end up non-null, triggering the assertion "Declaring both error and errorText is not supported." This happens because InputDecoration.copyWith() cannot clear fields (passing null means "keep existing value").

The fix explicitly creates a new InputDecoration with errorText set to null when errorBuilder is used, ensuring only one error display mechanism is active at a time.

Fixes #183378. When using errorBuilder alongside a decoration that has errorText, both error and errorText end up non-null, triggering the assertion "Declaring both error and errorText is not supported." This happens because InputDecoration.copyWith() cannot clear fields (passing null means "keep existing value"). The fix explicitly creates a new InputDecoration with errorText set to null when errorBuilder is used, ensuring only one error display mechanism is active at a time.

gemini-code-assist

Code Review

This pull request correctly fixes a crash that occurs when errorBuilder is used with a decoration that also defines errorText. The approach of creating a new InputDecoration instance to explicitly nullify errorText is sound. However, this has been implemented in a very verbose way in both DropdownButtonFormField and TextFormField, leading to significant code duplication. My review includes suggestions to refactor this logic to improve maintainability.

_{Note: Security Review is unavailable for this PR.}

gemini-code-assist · 2026-03-09T00:50:39Z

+             if (error != null) {
+               // When using errorBuilder, we need to explicitly clear errorText since
+               // copyWith cannot clear fields (null means "keep existing value").
+               effectiveDecoration = InputDecoration(
+                 error: error,
+                 errorText: null,
+                 hintText: hintText,
+                 icon: effectiveDecoration.icon,
+                 iconColor: effectiveDecoration.iconColor,
+                 label: effectiveDecoration.label,
+                 labelText: effectiveDecoration.labelText,
+                 labelStyle: effectiveDecoration.labelStyle,
+                 floatingLabelStyle: effectiveDecoration.floatingLabelStyle,
+                 helper: effectiveDecoration.helper,
+                 helperText: effectiveDecoration.helperText,
+                 helperStyle: effectiveDecoration.helperStyle,
+                 helperMaxLines: effectiveDecoration.helperMaxLines,
+                 hint: effectiveDecoration.hint,
+                 hintStyle: effectiveDecoration.hintStyle,
+                 hintTextDirection: effectiveDecoration.hintTextDirection,
+                 hintFadeDuration: effectiveDecoration.hintFadeDuration,
+                 hintMaxLines: effectiveDecoration.hintMaxLines,
+                 maintainHintHeight: effectiveDecoration.maintainHintHeight,
+                 maintainHintSize: effectiveDecoration.maintainHintSize,
+                 maintainLabelSize: effectiveDecoration.maintainLabelSize,
+                 errorStyle: effectiveDecoration.errorStyle,
+                 errorMaxLines: effectiveDecoration.errorMaxLines,
+                 floatingLabelBehavior: effectiveDecoration.floatingLabelBehavior,
+                 floatingLabelAlignment: effectiveDecoration.floatingLabelAlignment,
+                 isCollapsed: effectiveDecoration.isCollapsed,
+                 isDense: effectiveDecoration.isDense,
+                 contentPadding: effectiveDecoration.contentPadding,
+                 prefixIcon: effectiveDecoration.prefixIcon,
+                 prefix: effectiveDecoration.prefix,
+                 prefixText: effectiveDecoration.prefixText,
+                 prefixIconConstraints: effectiveDecoration.prefixIconConstraints,
+                 prefixStyle: effectiveDecoration.prefixStyle,
+                 prefixIconColor: effectiveDecoration.prefixIconColor,
+                 suffixIcon: effectiveDecoration.suffixIcon,
+                 suffix: effectiveDecoration.suffix,
+                 suffixText: effectiveDecoration.suffixText,
+                 suffixStyle: effectiveDecoration.suffixStyle,
+                 suffixIconColor: effectiveDecoration.suffixIconColor,
+                 suffixIconConstraints: effectiveDecoration.suffixIconConstraints,
+                 counter: effectiveDecoration.counter,
+                 counterText: effectiveDecoration.counterText,
+                 counterStyle: effectiveDecoration.counterStyle,
+                 filled: effectiveDecoration.filled,
+                 fillColor: effectiveDecoration.fillColor,
+                 focusColor: effectiveDecoration.focusColor,
+                 hoverColor: effectiveDecoration.hoverColor,
+                 errorBorder: effectiveDecoration.errorBorder,
+                 focusedBorder: effectiveDecoration.focusedBorder,
+                 focusedErrorBorder: effectiveDecoration.focusedErrorBorder,
+                 disabledBorder: effectiveDecoration.disabledBorder,
+                 enabledBorder: effectiveDecoration.enabledBorder,
+                 border: effectiveDecoration.border,
+                 enabled: effectiveDecoration.enabled,
+                 semanticCounterText: effectiveDecoration.semanticCounterText,
+                 alignLabelWithHint: effectiveDecoration.alignLabelWithHint,
+                 constraints: effectiveDecoration.constraints,
+                 visualDensity: effectiveDecoration.visualDensity,
+               );
+             } else {
+               effectiveDecoration = effectiveDecoration.copyWith(
+                 errorText: errorText,
+                 hintText: hintText,
+               );
+             }


While creating a new InputDecoration instance is the correct way to solve this issue (given that copyWith cannot nullify fields), this implementation is very verbose and hard to maintain. A nearly identical block of code has been added in text_form_field.dart, which introduces duplication.

To improve maintainability, consider extracting this logic into a shared helper function to avoid repeating this large constructor call.

gemini-code-assist · 2026-03-09T00:50:39Z

+                 ? InputDecoration(
+                     error: errorBuilder(state.context, errorText),
+                     errorText: null,
+                     icon: effectiveDecoration.icon,
+                     iconColor: effectiveDecoration.iconColor,
+                     label: effectiveDecoration.label,
+                     labelText: effectiveDecoration.labelText,
+                     labelStyle: effectiveDecoration.labelStyle,
+                     floatingLabelStyle: effectiveDecoration.floatingLabelStyle,
+                     helper: effectiveDecoration.helper,
+                     helperText: effectiveDecoration.helperText,
+                     helperStyle: effectiveDecoration.helperStyle,
+                     helperMaxLines: effectiveDecoration.helperMaxLines,
+                     hintText: effectiveDecoration.hintText,
+                     hint: effectiveDecoration.hint,
+                     hintStyle: effectiveDecoration.hintStyle,
+                     hintTextDirection: effectiveDecoration.hintTextDirection,
+                     hintFadeDuration: effectiveDecoration.hintFadeDuration,
+                     hintMaxLines: effectiveDecoration.hintMaxLines,
+                     errorStyle: effectiveDecoration.errorStyle,
+                     errorMaxLines: effectiveDecoration.errorMaxLines,
+                     floatingLabelBehavior: effectiveDecoration.floatingLabelBehavior,
+                     floatingLabelAlignment: effectiveDecoration.floatingLabelAlignment,
+                     isCollapsed: effectiveDecoration.isCollapsed,
+                     isDense: effectiveDecoration.isDense,
+                     contentPadding: effectiveDecoration.contentPadding,
+                     prefixIcon: effectiveDecoration.prefixIcon,
+                     prefix: effectiveDecoration.prefix,
+                     prefixText: effectiveDecoration.prefixText,
+                     prefixIconConstraints: effectiveDecoration.prefixIconConstraints,
+                     prefixStyle: effectiveDecoration.prefixStyle,
+                     prefixIconColor: effectiveDecoration.prefixIconColor,
+                     suffixIcon: effectiveDecoration.suffixIcon,
+                     suffix: effectiveDecoration.suffix,
+                     suffixText: effectiveDecoration.suffixText,
+                     suffixStyle: effectiveDecoration.suffixStyle,
+                     suffixIconColor: effectiveDecoration.suffixIconColor,
+                     suffixIconConstraints: effectiveDecoration.suffixIconConstraints,
+                     counter: effectiveDecoration.counter,
+                     counterText: effectiveDecoration.counterText,
+                     counterStyle: effectiveDecoration.counterStyle,
+                     filled: effectiveDecoration.filled,
+                     fillColor: effectiveDecoration.fillColor,
+                     focusColor: effectiveDecoration.focusColor,
+                     hoverColor: effectiveDecoration.hoverColor,
+                     errorBorder: effectiveDecoration.errorBorder,
+                     focusedBorder: effectiveDecoration.focusedBorder,
+                     focusedErrorBorder: effectiveDecoration.focusedErrorBorder,
+                     disabledBorder: effectiveDecoration.disabledBorder,
+                     enabledBorder: effectiveDecoration.enabledBorder,
+                     border: effectiveDecoration.border,
+                     enabled: effectiveDecoration.enabled,
+                     semanticCounterText: effectiveDecoration.semanticCounterText,
+                     alignLabelWithHint: effectiveDecoration.alignLabelWithHint,
+                     constraints: effectiveDecoration.constraints,
+                     visualDensity: effectiveDecoration.visualDensity,
+                   )


This large block for creating a new InputDecoration is very similar to the one added in dropdown.dart. This duplication makes the code harder to maintain.

To improve this, consider refactoring this logic into a shared helper function that can be used in both places. This would centralize the verbose constructor call and make future updates to InputDecoration easier to manage.

Hari-07 · 2026-03-09T02:59:01Z

Could you update the description to match the PR Template?

A much easier fix would be to just add an assert on these widgets to make sure both are not non-null in the constructor. That's a pattern we follow in other widgets as well

You will also need to add tests that trigger the assert

Mairramer · 2026-03-09T12:58:05Z

-               errorText: errorText,
-               hintText: hintText,
-             );
+             if (error != null) {


I believe it’s possible to use merge instead of recreating everything.

@Hari-07

This PR fixes a framework crash that occurs when `errorBuilder` is used alongside an `InputDecoration` that contains an `errorText`. Because `InputDecoration.copyWith` ignores `null` values, attempting to clear the `errorText` dynamically during the build phase leaves the decoration with both properties defined, triggering a late assertion in `InputDecorator`. Following the architectural guidance provided by @Hari-07 in PR #183384, this fix enforces mutual exclusivity at the constructor level. It adds an `assert` to both `TextFormField` and `DropdownButtonFormField` to ensure developers fail fast if both properties are provided. Fixes #183378 I added the following tests to verify the assertions: - `TextFormField` asserts when both `errorBuilder` and `decoration.errorText` are provided. - `DropdownButtonFormField` asserts when both `errorBuilder` and `decoration.errorText` are provided. --------- Co-authored-by: Hari07 <22373191+Hari-07@users.noreply.github.com>

@Hari-07

…#183901) This PR fixes a framework crash that occurs when `errorBuilder` is used alongside an `InputDecoration` that contains an `errorText`. Because `InputDecoration.copyWith` ignores `null` values, attempting to clear the `errorText` dynamically during the build phase leaves the decoration with both properties defined, triggering a late assertion in `InputDecorator`. Following the architectural guidance provided by @Hari-07 in PR flutter#183384, this fix enforces mutual exclusivity at the constructor level. It adds an `assert` to both `TextFormField` and `DropdownButtonFormField` to ensure developers fail fast if both properties are provided. Fixes flutter#183378 I added the following tests to verify the assertions: - `TextFormField` asserts when both `errorBuilder` and `decoration.errorText` are provided. - `DropdownButtonFormField` asserts when both `errorBuilder` and `decoration.errorText` are provided. --------- Co-authored-by: Hari07 <22373191+Hari-07@users.noreply.github.com>

@Hari-07

…#183901) This PR fixes a framework crash that occurs when `errorBuilder` is used alongside an `InputDecoration` that contains an `errorText`. Because `InputDecoration.copyWith` ignores `null` values, attempting to clear the `errorText` dynamically during the build phase leaves the decoration with both properties defined, triggering a late assertion in `InputDecorator`. Following the architectural guidance provided by @Hari-07 in PR flutter#183384, this fix enforces mutual exclusivity at the constructor level. It adds an `assert` to both `TextFormField` and `DropdownButtonFormField` to ensure developers fail fast if both properties are provided. Fixes flutter#183378 I added the following tests to verify the assertions: - `TextFormField` asserts when both `errorBuilder` and `decoration.errorText` are provided. - `DropdownButtonFormField` asserts when both `errorBuilder` and `decoration.errorText` are provided. --------- Co-authored-by: Hari07 <22373191+Hari-07@users.noreply.github.com>

github-actions Bot added a: text input Entering text in a text field or keyboard related problems framework flutter/packages/flutter repository. See also f: labels. f: material design flutter/packages/flutter/material repository. labels Mar 9, 2026

gemini-code-assist Bot reviewed Mar 9, 2026

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Mairramer reviewed Mar 9, 2026

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04cb closed this by deleting the head repository Mar 10, 2026

muradhossin mentioned this pull request Mar 19, 2026

Add assert for mutually exclusive errorBuilder and errorText #183901

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Fix crash when errorBuilder is used with decoration containing errorText#183384

Fix crash when errorBuilder is used with decoration containing errorText#183384
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04cb:fix/error-builder-copywith

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