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.

最后我发现没有一个应用程序被成功安装，不仅仅是我的。我将SD卡默认的安装应用程序设置为自动。这就解决了问题。

我也遇到过这个问题。 请尝试这个解决方案。确保您的项目的包名称不同于您的移动电话中已经安装的以前的项目。我觉得他们的名字有冲突。它在我身上起作用。

我的问题是:我使用了调试Apk，这是在我从Android Studio执行Run命令时生成的

解决方案是:不使用此文件，清除项目并单击Build > Build APK(s) from Android Studio。然后你可以使用生成的APK从通常的文件夹(app/build/outputs/ APK /debug/)

像这样生成的文件安装起来没有问题。

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

有时存储不可用也是应该提到的，因为我面临这个问题，因为需要安装的设备没有足够的空间，而且系统也没有提醒用户。你可以通过调试找到答案