我用2个不同的证书为应用程序签名，所以用旧证书删除旧版本，然后重新安装新证书为我解决了这个问题

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。

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。

就我而言，这是因为我使用的是支持库28的alpha版本。看起来谷歌将这些预发布版本标记为testOnly。如果你真的想这样发布(例如，你想像我一样推出一个内部测试)，你可以将这一行添加到你的gradle中。属性文件:

android.injected.testOnly=false

确保考虑到以下建议:

Your build variants and Flavors should be same(App installed and new one), usually release Signature file must be the same(*.jks file) The version you set in build.gradle or AndroidManifest have greater value compared to current version(it is recommended to set version in build.gradle) URL is correct(doesn't have typo) and server is reachable(WebService/WebMethod/WIFI is running/available and ...) File downloaded completely File saved correctly into desired directory Setting for Data and Type in setDataAndType is correct

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.