Multiple widgets used the same GlobalKey

Why This Happens

In Flutter, each GlobalKey must be associated with exactly one widget at a time. This error often occurs in animated lists or when conditionally showing widgets that share a key. Ensure each widget gets its own unique key instance.

The Problem

final _formKey = GlobalKey<FormState>();
// In a PageView where both pages exist simultaneously:
PageView(
  children: [
    Form(key: _formKey, child: page1Fields()),
    Form(key: _formKey, child: page2Fields()),
  ],
)

The Fix

final _formKey1 = GlobalKey<FormState>();
final _formKey2 = GlobalKey<FormState>();
PageView(
  children: [
    Form(key: _formKey1, child: page1Fields()),
    Form(key: _formKey2, child: page2Fields()),
  ],
)

Step-by-Step Fix

1. 1

   Identify the error

   Look at the error message: Multiple widgets used the same GlobalKey. Two live widgets share a key.

2. 2

   Find the cause

   Check if a GlobalKey is reused across multiple widgets that can exist in the tree simultaneously.

3. 3

   Apply the fix

   Create separate GlobalKey instances for each widget, or restructure to ensure only one widget uses the key at a time.