'upgrade.disable-web' => true, in config.phpweb updater should be disabled
web updater opens and offers update
Operating system:
Debian 9
Web server:
apache
Database:
mariadb
PHP version:
7.3
Nextcloud version: (see Nextcloud admin page)
17.0.1
Updated from an older Nextcloud/ownCloud or fresh install:
updated
Login as admin user into your Nextcloud and access
http://example.com/index.php/settings/integrity/failed
paste the results here.
No errors have been found.

upgrade.disable-web will disable above page (occ upgrade from cli) via web. Web based updater will still work and is available for admins. If the above page is disabled everything works as expected.
@zeigerpuppy Do you think we should introduce a setting like upgrade.disable-web-updater for your use case?
An option for disabling the web updater would be really useful.
We've found the cli updater to be more reliable for our purposes and it'd be a useful safety feature to prevent less experienced admins on our platform from mistakedly trying the web updater.
This issue has been automatically marked as stale because it has not had recent activity and seems to be missing some essential information. It will be closed if no further activity occurs. Thank you for your contributions.
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An option for disabling the web updater would be really useful.
We've found the cli updater to be more reliable for our purposes and it'd be a useful safety feature to prevent less experienced admins on our platform from mistakedly trying the web updater.
Also some distribute the server via external means and could disable this way of update/upgrade entirely.
Closing because 'upgrade.disable-web' => true, works as expected (disable occ upgrade from web). @gary-kim created a feature request at nextcloud/updater to disable the web based updater.
Updater: Download a nextcloud update and move the files in place.
Upgrade: Populate the database changes to nextcloud and run maintenance / after update jobs.
If you need to disable the web based updater now I would suggest to block access to /updater/index.php until one implemented the linked feature request.
Most helpful comment
An option for disabling the web updater would be really useful.
We've found the cli updater to be more reliable for our purposes and it'd be a useful safety feature to prevent less experienced admins on our platform from mistakedly trying the web updater.