title: How to Fix Android App Not Installed Error?
body: <p>I have developed the app by Android Studio, and build it to signed apk with V1 and V2.
  <br/>
  It could install in my phone successfully.
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  But, when I uninstall the app, and install the app again, it would show App not installed.
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  But the apk file is the same apk file. Why first time can install, but not successful in second time?
  <br/>
  Now, when I see this error, I would change the versionCode, then the app could install.
  <br/>
  But beside this solution, have any solution on this problem?
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  Thank you so much!</p>