When running [Optimizely DXP](🔗), you can create a customized maintenance page, to be displayed if you have to take down the site during for example deployments.  Create an HTML page called _maintenancepage.htm_, and add it in the root directory of your application, to be used for deployments.
This maintenance page cannot use any other files in the environment. Resources such as CSS, JavaScript, images must either be hosted somewhere else or embedded in the HTML file to be visible during maintenance.
Note
Prior to Optimizely Content Management System (CMS) version 12, the maintenance file size should be between 512 bytes and 1 MB. CMS version 12 removes this restriction.
If you do not add this file, a generic maintenance page is used.
See also:
[Environment configurations](🔗)
[Deploying: Important notifications](🔗)