when I tried to update my applcation with new version that has same signature as previous one, shows above error.
What I am missing?
If you install the application on your device via
adb install you should look for the reinstall option which should be
-r. So if you do
adb install -r you should be able to install without uninstalling before.
You are getting that error because an application with a package name same as your application already exists. If you are sure that you have not installed the same application before, change the package name and try.
Else wise, here is what you can do: