我正在开发一个应用程序，使用以下xml。这是我的登录片段的xml。但是，当我尝试清理/构建项目时，会出现以下错误：
错误：分析xml时出错：格式不正确（无效标记）

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:app="http://schemas.android.com/apk/res-auto"
tools:context=".SignInFragment"
android:background="@drawable/gradient_color">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<ImageButton
android:id="@+id/sign_up_close_btn"
android:layout_width="50dp"
android:layout_height="50dp"
android:background="@android:color/transparent"
android:padding="16dp"
android:src="@drawable/ic_cancel"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="1.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<ImageView
android:id="@+id/imageView"
android:layout_width="254dp"
android:layout_height="182dp"
android:src="@mipmap/ic_launcher_foreground"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.496"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.16000003" />
<EditText
android:id="@+id/sign_in_email"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginStart="16dp"
android:layout_marginLeft="16dp"
android:layout_marginTop="32dp"
android:layout_marginEnd="16dp"
android:layout_marginRight="16dp"
android:backgroundTint="#70FFFFFF"
android:textColor="@color/colorAccent"
android:ems="10"
android:hint="@string/hint_email"
android:inputType="textEmailAddress"
android:textColorHint="#70FFFFFF"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/imageView" />
<EditText
android:id="@+id/sign_in_pass"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginStart="16dp"
android:layout_marginLeft="16dp"
android:layout_marginTop="32dp"
android:layout_marginEnd="16dp"
android:layout_marginRight="16dp"
android:backgroundTint="#70FFFFFF"
android:textColor="@color/colorAccent"
android:ems="10"
android:hint="@string/hint_pass"
android:inputType="textPassword"
android:textColorHint="#70FFFFFF"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/sign_in_email" />
<TextView
android:id="@+id/sign_in_forgot_pass"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="4dp"
android:layout_marginLeft="4dp"
android:text="@string/forg_pass"
android:textColor="@color/colorAccent"
app:layout_constraintStart_toStartOf="@+id/sign_in_pass"
app:layout_constraintTop_toBottomOf="@+id/sign_in_pass" />
<Button
android:id="@+id/sign_in_btn"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginStart="16dp"
android:layout_marginLeft="16dp"
android:layout_marginEnd="16dp"
android:layout_marginRight="16dp"
android:background="@color/colorPrimary"
android:text="@string/btn_In"
android:textAllCaps="false"
android:textColor="@color/colorAccent"
android:textSize="16sp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/sign_in_forgot_pass"
app:layout_constraintVertical_bias="0.47000003" />
<TextView
android:id="@+id/textView2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="16dp"
android:text="@string/or"
android:textColor="@color/colorAccent"
app:layout_constraintBottom_toTopOf="@+id/tv_dont_have_an_account"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.498"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/sign_in_btn"
app:layout_constraintVertical_bias="0.0" />
<TextView
android:id="@+id/tv_dont_have_an_account"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginBottom="24dp"
android:text="@string/text1"
android:textColor="@color/colorAccent"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent" />
<View
android:id="@+id/divider"
android:layout_width="100dp"
android:layout_height="1dp"
android:layout_marginEnd="16dp"
android:layout_marginRight="16dp"
android:background="@color/colorAccent"
app:layout_constraintBottom_toBottomOf="@+id/textView2"
app:layout_constraintEnd_toStartOf="@+id/textView2"
app:layout_constraintTop_toTopOf="@+id/textView2" />
<View
android:id="@+id/divider2"
android:layout_width="100dp"
android:layout_height="1dp"
android:layout_marginStart="16dp"
android:layout_marginLeft="16dp"
android:background="@color/colorAccent"
app:layout_constraintBottom_toBottomOf="@+id/textView2"
app:layout_constraintStart_toEndOf="@+id/textView2"
app:layout_constraintTop_toTopOf="@+id/textView2" />
<ProgressBar
android:id="@+id/sign_in_progress_bar"
style="?android:attr/progressBarStyle"
android:layout_width="30dp"
android:layout_height="30dp"
android:visibility="invisible"
app:layout_constraintBottom_toTopOf="@+id/sign_in_btn"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/sign_in_pass" />
</>
</FrameLayout>

可能是什么意思？我做错了什么？我真的很担心。我已经检查了我的代码很多次，但没有找到错误