The activity must be exported or contain an intent-filter

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just add intent-filter Tag inside your activity

for example ::

    <activity
android:name=".activityName">
<intent-filter>
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>

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Double check your manifest, your first activity should have tag

    <intent-filter>
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>

inside of activity tag.

If that doesn't work, look for target build, which located in the left of run button (green-colored play button), it should be targeting "app" folder, not a particular activity. if it doesn't targeting "app", just click it and choose "app" from drop down list.

Hope it helps!

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I changed the Select Run/Debug Configuration from my MainActivity to App and it started working. Select App configuration snapshot:

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Just Select App from dropdown menu with Run(green play icon). it will run the whole the App not the specific Activity. if it doesn't help try to use in that activity in ManiFest.xml file. thankyou

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In manifest.xml, select activity which u wanna start e set this informations:

    <intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>

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Check your manifest,Open the file with .xml extension and then all your activities are listed your first activity should have this code enclosed in its tags

<intent-filter>
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>

or there is another way u can choose from configuration which is drop down list on the left side of run button choose from App from it Hope it will help!!

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it's because you are trying to launch your app from an activity that is not launcher activity. try run it from launcher activity or change your current activity category to launcher in android Manifest.

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First check a Launch Activity is set in your 'manifest.xml' file has:

<activity android:name=".{activityName}">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>

If this is set correctly, next check your run/debug configuration is set to 'App',

If the 'App' configuration is missing - you will need to add it by first selecting 'Edit Confurations'

If you do not have a 'App' configuration you will need to create one, else select you 'App' configuration and skip the creating steps. Also if your configuration is corrupt you may need to delete it but first backup your project. To delete a corrupt configuration, select it by expanding the 'Android App' node and chose the '-' button.

To create a new configuration, select the '+' button and select 'Android App'

If you have just created the configuration you will be presented with the following default name value of 'Unnamed' and module will have the value '<no module>' then hit 'Apply' and 'OK'.

Set this the name to 'App' and select 'app' as the module.

Next select 'App' as the run configuration and Run.

Thats it!

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Sometimes if you change the starting activity you have to click edit in the run dropdown play button and in app change the Launch Options Activity to the one you have set the LAUNCHER intent filter in the manifest.

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If you're trying to launch a specific activity instead of running the launcher one. When you select that activity. the android studio might through this error, Either you need to make it launcher activity, just like answered by few others. or you need to add android:exported="true" inside your activity tag inside manifest. It allows any external tool to run your specific activity directly without making it a launcher activity