ParseError at [row,col]:[66,34] Message: -xml-names-19990114#AttributeNSNotUnique?Button&layout_column

Question

I have an error with my app the error says

    ParseError at [row,col]:[66,34] Message:         http://www.w3.org/TR/1999/REC-xml-names-19990114#AttributeNSNotUnique?        Button&layout_column 

I can't find where the error is.. I don't know which are the row and col... maybe in the xml files?

This is the AndroidManifest file

    AndroidManifest.xml
    <?xml version="1.0" encoding="utf-8"?>
    <manifest     xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.***">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="App Name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
    <activity
        android:name="com.example.appname.MainActivity"
        android:theme="@style/Theme.AppCompat.NoActionBar"
        android:screenOrientation="portrait">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER"    />
        </intent-filter>
    </activity>
    <!-- Sample AdMob App ID: ca-app-pub-3940256099942544~3347511713 -->

        <meta-data
            android:name="appname"
            android:value="ca-app-pub-2703074771097768~4557375307"/>. 
    </application>

Answer 1

I had similar issue:

ParseError at [row,col]:[8,279]
Message: http://www.w3.org/TR/1999/REC-xml-names-19990114#AttributeNSNotUnique?androidx.constraintlayout.widget.ConstraintLayout&layout_width&http://schemas.android.com/apk/res/android

What you need to do:

First read the error message carefully, in my case it's mentioned in error message that there is something wrong with: ConstraintLayout&layout_width attribute in my latest layout xml file.

In my case I had mistakenly added layout_height and layout_width attributes to <layout> tag, which is actually meant only for data binding. So just by removing those lines I was able to fix this issue.

The layout that I initially had:

<layout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

To fix this issue I did:

<layout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">

Answer 2

As the answer here explains, the error you're getting is getting obscured by an updated version of Gradle. In my case, I also had the [row][col] message, and when I downgraded my Gradle version from 4.2.2 to 4.1.3 and compiled again, it now showed me the real error (I had a duplicated attribute in one of my XMLs) and I was able to solve it.