Please transfer a valid prop path to form item

 <el-form-item v-for="(item, index) in formData.picSize" :key="item.title" :label="item.title" class="yydh-bili">
                <el-form-item
                    :prop="'item.' + index + '.width'"
                    :rules="picRules"
                >
                    <el-input v-model="item.width" style="width: 80px; margin-right: 10px;"></el-input>
                    <span>：</span>
                </el-form-item>
                <el-form-item
                    :prop="'item.' + index + '.height'"
                    :rules="picRules"
                >
                    <el-input v-model="item.height" style="width: 80px; margin-right: 10px;"></el-input>
                </el-form-item>
</el-form-item>


<script>
formData: {
                picSize: [
                    {
                        name:'ACTIVITYBIGSIZE',
                        title: 'title1',
                        width: 4,
                        height: 3,
                    },
                    {
                        title: 'title2',
                        width: 4,
                        height: 3,
                    },
                ],
}

</script>

The solution is to change the definition of the form’s data proformitemsize

 <el-form-item v-for="(item, index) in formData.picSize" :key="item.title" :label="item.title" class="yydh-bili">
                <el-form-item
                    <!--Im here-->
                    :prop="'picSize.' + index + '.width'"
                    :rules="picRules"
                >
                    <el-input v-model="item.width" style="width: 80px; margin-right: 10px;"></el-input>
                    <span>：</span>
                </el-form-item>
                <el-form-item
                     <!--Im here-->
                    :prop="'picSize.' + index + '.height'"
                    :rules="picRules"
                >
                    <el-input v-model="item.height" style="width: 80px; margin-right: 10px;"></el-input>
                </el-form-item>
</el-form-item>

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