Release new version of android app

Question

I released new version of my application in eclipse with own signature and i increase version code.

When i want to install new version on device that installed old version on it,this message appears:

"an existing package with the same name with a conflicting signature is already installed."

Answer 1

The reason might be because you previously installed a debug version on your device which has a default key used by that debug version. Releasing a new version with your signature doesn't match the debug key so you get that warning and should uninstall current version before installing the new one.

Answer 2

The key is

...of my application in eclipse with own signature...

if the signature is different than you used before, for any reason, you cannot install application with the same id (package name), unless you uninstall the old app first.