You'll know the upgrade is over when the following message "upgrade complete.
Please check your front office theme is functional (try to make an order, check theme)" appears in green, along with the following final log entry: "End of process".
You can quickly see whether an update is required or not.
If you know that there is a more recent version available than the one presented, you can trigger a version check by clicking the "Check if a new version available" button.
Nevertheless, you can improve the lifespan of your custom code by turning it into overriding files.
See the developer documentation for more information. Once the upgrade process is launched, the whole configuration page is replaced by two sections: "Activity Log" and "Rollback".
Note that the 1-Click Upgrade module performs its own set of backup in order to allow for reverting of the whole upgrade. The "pre-Upgrade checklist" section gives you useful information on your current Presta Shop installation, and how it might interact with the automatic upgrade.), the auto-upgrade module understands that the maintenance mode is not required, since no one else than you can access the site.Therefore, if you want to update from a 1.4.x version to the latest 1.6.x version, you must click on the "More options (Expert mode)" button.This will open a new section, named "More options (expert mode)", where you can choose the distribution channel to which you want to update.The safest way is to have an exact copy of your shop available, either on your local computer or in another folder of your web server.It should contain all your products, categories, themes, modules, translations, settings, etc. Once the upgrade is done, browse your front and back office thoroughly to make sure that everything is as expected.
If not, then the upgrade tool has an issue with your configuration, and you should use the manual upgrade method, which is now deprecated and takes longer, but which may help in your situation.