Please install "Extension: MobileDetect" for Vietnamese Wikibooks!
I don't see which underlying problem this would solve?
Also see https://www.mediawiki.org/wiki/Writing_an_extension_for_deployment for all the required steps, as this non-stable extension is not on any Wikimedia site yet.
Unfortunately closing this Phabricator task as no further information and no community consensus has been provided.
@lamducanh: After you have provided the information asked for and if this still happens, please set the status of this task back to "Open" via the Add Action... → Change Status dropdown. Thanks!