thanks for your answer actually here is my full configuration to bypass ownCloud’s upgrade and apps upgrade, I added the official comments to explain their purpose.
* Disable the web based updater
'upgrade.disable-web' => true,
* Automatic update of market apps, set to "false" to disable.
'upgrade.automatic-app-update' => false,
* Check if ownCloud is up-to-date and shows a notification if a new version is
* available. This option is only applicable to ownCloud core. It is not
* applicable to app updates.
'updatechecker' => false,
* URL that ownCloud should use to look for updates
'updater.server.url' => '127.0.0.1' // I add this one now since upgrade.disable-web does not work
So, to sum up the main problem here was that even with ‘upgrade.disable-web’ => true I would have the “upgrade button” in the admin page (but not the notification since I have ‘updatechecker’ => false). I add now ‘updater.server.url’ => ‘127.0.0.1’ so even if it shows the button, once you click, it answers very fast “No updates found online.” and I’m sure to keep a full automated control. I’m not very “proud” of that but at least it’s a dirtfix and I don’t screw the overall speed.
I already don’t use updatenotification app
Anyway the main problem here is that ‘upgrade.disable-web’ => true should never show the upgrade button in the admin.