frequent issues arising in android view, Error parsing XML: unbound prefix

user_243782 0
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I have frequent problem in android view, Error parsing XML: unbound prefix on Line 2.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout android:orientation="vertical" android:id="@+id/myScrollLayout" 
android:layout_width="fill_parent"  android:layout_height="wrap_content">
    <TextView android:layout_height="wrap_content" android:layout_width="fill_parent" 
    android:text="Family" android:id="@+id/Family" 
    android:textSize="16px" android:padding="5px" 
    android:textStyle="bold" android:gravity="center_horizontal">
    </TextView>

    <ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="fill_parent" android:layout_height="wrap_content"
        android:orientation="vertical" android:scrollbars="vertical">
        <LinearLayout android:orientation="vertical" android:id="@+id/myMainLayout" 
        android:layout_width="fill_parent"  android:layout_height="wrap_content">
        </LinearLayout>
    </ScrollView>

</LinearLayout>
eclipse android-linearlayout android xml
16 Answers

A couple of reasons that this can happen:

1) You see this error with an incorrect namespace, or a typo in the attribute. Like 'xmlns' is wrong, it should be xmlns:android

2) First node needs to contain: xmlns:android="http://schemas.android.com/apk/res/android"

3) If you are integrating AdMob, check custom parameters like ads:adSize, you need

xmlns:ads="http://schemas.android.com/apk/lib/com.google.ads"

4) If you are using LinearLayout you might have to define tools:

xmlns:tools="http://schemas.android.com/tools"

user_2437820

As you mention, you need to specify the right namespace. You also see this error with an incorrect namespace.

<?xml version="1.0" encoding="utf-8"?>
<ScrollView xmlns="http://schemas.android.com/apk/res/android"
         android:layout_width="fill_parent"
         android:layout_height="fill_parent"
         android:padding="10dip">

will not work.

Change:

xmlns="http://schemas.android.com/apk/res/android"

to

xmlns:android="http://schemas.android.com/apk/res/android"

The error message is referring to everything that starts "android:" as the XML does not know what the "android:" namespace is.

xmlns:android defines it.

VonC_63090

OK, there are lots of solutions here but non actually explain the root cause of the problem so here we go:

when you see an attribute like android:layout_width="match_parent" the android part is the prefix, the format for an attribute here is PREFIX:NAME="VALUE". in XML, namespaces and prefixes are ways to avoid naming conflicts for example we can have two distinct attributes with same name but different prefixes like: a:a="val" and b:a="val".

to use prefixes like android or app or any other your should define a namespace using xmlns attribute.

so if you have this issue just find prefixes that do not have a namespace defined, if you have tools:... you should add tools namespace as some answeres suggested, if you have app:... attribute you should add xmlns:app="http://schemas.android.com/apk/res-auto" to the root element

Further reading:

XML Namespaces simple explanation

XML Namespaces in W3

user_8872770

I got this error in Xamarin when I was using 

  <android.support.v7.widget.CardView  
    android:layout_width="match_parent"  
    android:layout_height="wrap_content"  
    card_view:cardElevation="4dp"  
    card_view:cardCornerRadius="5dp"  
    card_view:cardUseCompatPadding="true">  
  </android.support.v7.widget.CardView>

in a layout file without installing the nuget package for android.support.v7.widget.CardView

Installing the applicable nuget package fixed the issue. Hope it helps, I didn't see this answer anywhere in the list

user_105043070
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