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.

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

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。

对我来说，原因是我在同一部手机上使用不同的构建变体进行了多个构建:

所发生的事情是，其中一些构建是由我构建的，另一个是由另一个开发人员发给我的。试图安装开发人员，而我有其他构建(由我构建)导致上述错误。

所以修复很简单:删除我手机上的所有构建(不管构建变体)..然后安装我的同事发来的apk ..而且效果很好

我也解决了这个问题，

问题是我两次宣布了我的主要活动， On作为第一个要加载的活动，我还为它指定了一个意图过滤器 在下面我又声明了一遍。

只要确保你不会重复申报你的活动。

检查Android版本。

如果你安装的是非市场应用程序，和不兼容的版本，你会得到这个错误。

应用程序的目标是2.3.4 您的设备是2.2 然后你会得到这个错误。