By default DokuWiki checks a special URL for messages once a day. This message system is used to notify administrators of DokuWiki installations about new releases and security warnings.
When the ACL is enabled , messages are displayed only to superusers. If ACL is disabled, all users can see the message.
The feature needs to contact update.dokuwiki.org on Port 80 - make sure your firewall allows this. If you dont want this feature, you can disable it with the updatecheck option.
Each message has a unique ID shown in square brackets. Only messages which have a higher ID than the one configured in conf/msg will be shown. When you upgrade to the release announced in the message, the conf/msg file will be upgraded as well, suppressing the message. If you don't want to upgrade to an announced release you can simply increase the number in conf/msg.
When upgrading your installation, it might happen that DokuWiki continues to show the update message, even though the number in conf/msg was increased by the upgrade. This is because DokuWiki caches already fetched messages for a day and will only refetch if the last modified timestamp of conf/msg is higher than the one of the cache file. To stop the outdated update message from showing you can simply wait a day, touch1) the conf/msg or delete the data/cache/messages.txt cache file.