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"Error running app: Default Activity not Found"

I'm programming an app with sqlite+JSON, but suddenly I couldn't Run it anymore, and it popped this message, here's my AndroidManifest.xml , Idk if there's something wrong with it, my main activity is called DatosActivity, I wish you could help me.
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.hitan.practica2_u3">
<application
android:allowBackup="true"
android:icon="#mipmap/ic_launcher"
android:label="#string/app_name"
android:supportsRtl="true"
android:theme="#style/AppTheme">
<activity
android:name="com.example.hitan.practica2_u3.DatosActivity"
android:theme="#style/AppTheme.NoActionBar"></activity>
</application>
</manifest>

You should add category.LAUNCHER & action.MAIN .
<activity
android:name="com.example.hitan.practica2_u3.DatosActivity"
android:theme="#style/AppTheme.NoActionBar"
>
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>

This error is coming because you have not added the default screen which should execute first. So try adding following code snippet, and your problem will be solved:
<activity
android:name="com.example.hitan.practica2_u3.DatosActivity"
android:theme="#style/AppTheme.NoActionBar">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
Hope it helps.

Please Add Intent Filter Tag in Manifest To Make It Default while Launching.

Add this intent filter inside your activity tag
<activity
android:name="com.example.hitan.practica2_u3.DatosActivity"
android:theme="#style/AppTheme.NoActionBar">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>

App is installed and has two icons

I made a android app and it worked very well, but there are two icons in my device screen. I think it could be a AndroidManifest problem. Any idea what it could be?
This my AndroidManifest.xml:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="pk.aeh.ideos.taa"
android:versionCode="1"
android:versionName="1.0" >
<application
android:icon="#drawable/icon"
android:label="#string/app_name"
android:theme="#android:style/Theme.NoTitleBar" >
<activity
android:name=".Ghinho_congviecActivity"
android:label="#string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:name="Nhap_congviecActivity"></activity>
<activity android:name="Sua_congviecActivity"></activity>
<activity
android:name=".Quizzes"
android:launchMode="singleTask">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:name=".PlayGame" />
<activity android:name=".Result" />
</application>
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

This could be because you have declared two activities as MAIN and LAUNCHER
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
in your Androidmanifest.xml file. You need to have only one activity with these intent filters so that when the app is installed the system will know which activity is to be used as the main launcher activity.

It is. You have two of these:
<category android:name="android.intent.category.LAUNCHER" />
Get rid of the one you don't want.

You need to make these changes to your Manifest.xml
<activity
android:name=".Ghinho_congviecActivity"
android:label="#string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:name="Nhap_congviecActivity"></activity>
<activity android:name="Sua_congviecActivity"></activity>
<activity
android:name=".Quizzes"
android:launchMode="singleTask">
</activity>
I am assuming that the Activity with the attribute android:label="#string/app_name" might be your main activity.

It could be because you have changed your package name and installed it twice with different package names.

Remove the intent filter of one the activity and it would work perfectly.!

Your manifest file should only have one activity with below Intent Filter, Activity which you want to have an icon:
<intent-filter>
<action android:name = "android.intent.action.MAIN" />
<category android:name = "android.intent.category.LAUNCHER" />
</intent-filter>
Based on your description, it sounds like two activities have this line. Check your Manifest...

You can declare only one Intent filter in the activity, on AndroidManifest.
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
If you used two or more intent filter in AndroidManifest, then you will have display 2 app icon, So remove it & set one intent filter.
I hove this is usedful to you.

android: No Launcher activity found

My AndroidManifest.xml is like the followings:
<application android:label="droid VNC server" android:icon="#drawable/icon"
android:name="MainApplication" android:debuggable="true">
<activity android:name=".MainActivity" android:launchMode="singleInstance"
android:label="#string/app_name" android:icon="#drawable/icon">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
<action android:name="org.onaips.vnc.ACTIVITY_UPDATE" />
</intent-filter>
</activity>
</application>
I already set the following two lines:
Why I still get the errors
No Launcher activity found
The launch will only sync the application package on the device
Thanks

Your intent-filter tag in xml file should exactly be like this:
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
Place it inside <activity> tag and you should be ok

Remove the line
<action android:name="org.onaips.vnc.ACTIVITY_UPDATE" />
Because there are 2 similar lines, the 2nd line is usually considered. (Ambiguity). So just remove that line, and you will see the app in the launcher!

no launcher activity was found even if i had declared one in the manifest

i declared the report file as my launcher. so its supposed to launch first when the app is started first. or do i get something wrong.
i get the error. no launch activity was found. thx guys
<activity android:name=".report" android:label="#string/app_name">
<intent-filter>
<action android:name="android.intent.action.REPORT" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:name=".Main" android:label="#string/app_name">
<intent-filter>
</intent-filter>
</activity>

You need to change the action:name from .REPORT to .MAIN. The action name corresponds to the intent action and not to the Activity name.
Fixed version of the above:
<activity android:name=".report" android:label="#string/app_name">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:name=".Main" android:label="#string/app_name">
</activity>

Android: No Launcher activity found! was working before

I have the same problem everyone reports but this began happening suddenly. My app was working as expected, automatically launching the MAIN activity.
But all of the sudden it stopped working and I started seeing the No Launcher activity found! message.
This is my Manifest:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.xitrica.android">
<uses-permission android:name="android.permission.INTERNET" />
<uses-sdk android:minSdkVersion="8" />
<application android:icon="#drawable/icon" android:label="#string/app_name"
android:theme="#style/Theme.Transparent">
<uses-library android:name="com.google.android.maps" android:required="true" />
<activity android:name="ElBusetonActivity" android:label="#string/app_name">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.DEFAULT" />
<category android:name="andoid.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:name="RouteInfoActivity"></activity>
<activity android:theme="#android:style/Theme.Translucent.NoTitleBar"
android:name="GetDirectionsActivity"></activity>
<activity android:theme="#android:style/Theme.Dialog"
android:name="PointProviderList"></activity>
</application>
</manifest>
Sorry if I'm not posting this snippet correctly. It's the first time I ever post a question.
Thanks in advance.

<activity android:name=".ElBusetonActivity" android:label="#string/app_name">
try this, prefix (".") on activity name
here (.) refer to package path

Remove
category android:name="android.intent.category.DEFAULT"
as it is not required.

Say if you have the Activity names TestActivity
If you want the TestActivity to be the first to launch when you hit "run", simply add two lines:
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
To the position like below in your AndroidManifest.xml:
<activity
android:name="TestActivity"
android:label="#string/name"
android:screenOrientation="portrait" >
<intent-filter android:label="#string/app_name" >
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>

use the dot before the activities in your manifest to declare it. or you can write the package name dot your activity name.
like this.........
<activity android:name=".ElBusetonActivity" android:label="#string/app_name">
if you not using package name then it decide the default one.