App not installed. An existing package by the same name with a conflicting signature
I have installed an apk file previously and now intend to install another updated apk file to my android phone. However the installation of the new apk file failed with message "an existing package by the same name with a conflicting signature is already installed".
I had tried to uninstall the first apk and then install the new apk file but the installation failed with the same message appeared. My phone is not rooted. Is there any way to rectify the error ?
Thank you in advance.