在我的情况下，我已经声明我的发射器活动为android:exported="false"

<activity android:name=".MainActivity"
            android:exported="false">

我最近瞄准了android 12，不得不把android:exported属性放在我的manifest组件中，但不知道该把什么作为值。将值更改为android:exported="true"有效。

在我的例子中，这是因为Android Studio 3.0设置Android:testOnly="true"在apk上，从版本build Variant构建。

https://commonsware.com/blog/2017/10/31/android-studio-3p0-flag-test-only.html

所以运行。/gradlew assemblerrelease来解决我的问题

我也面临着同样的问题。问题是我的AndroidManifest.xml文件中的主要活动写了两次。我删除了副本。

Clearly there are many causes of this problem. For me the situation was this: I had deployed to my nexus 7 (actual device) from within the Android Studio (v1.3.2). All worked fine. I then created a signed apk and uploaded to my Google Drive. After disconnecting my nexus from the usb, I went to the settings/apps and uninstalled my app (App1). I then opened google drive and clicked on my App1.apk and chose to install it (need to ensure you have allowed installation of apks in settings). Then I got the dreaded message "App not Installed"

Solution for me: go back into settings/apps and scroll though all apps and at the bottom was a pale version of my App1 (note the original App1 was at the top in Alphabetical order which was deleted as above). When clicking on the pale version it said "Not installed for this user". (I had set up my nexus to have more than one user). But in the top right corner there is a three dot button. I pressed this and it said "Uninstall for all users". Which I did and it fixed the problem. I was now able to click on App1.apk and it installed fine without the error.

当这个问题发生在我身上时，我通过删除项目文件夹中一些不重要的文件来解决它，比如密钥库。

事后看来，把你游戏的钥匙给别人可能不是什么好事。

如果您有该应用程序的以前版本，请先尝试删除它，现在我的问题已通过该方法解决。