If a user has turned on automatic updates for your app, the update will be downloaded and installed automatically.
App updates take some time to be delivered to existing users.
Once the update is published, your update will start being distributed to existing users.
Once your update is available, users can download the update on your app’s store listing page or from their My apps page on the Play Store app.
This is the one case, but there are lots of such issues in that case there is no proper documentation given neither they are helping developers via email.
While it isn't technically required, we strongly suggest increasing your application's version number each time you release your app.
But its been more than 4 days it is showing processing update and update has not gone live yet. I have sent a mail to the play store team but there is no revert yet Hi Akshay, I am also facing exact same issue.
I sent email to Google Support also but they are not replying at all.
For example, increment your version from 18.104.22.168 to 22.214.171.124.
You can adjust this setting on the "App Info" tab of your Andromo project's settings.