Use this tag for questions about putting your application on maintenance mode and/or displaying maintenance pages to end-users. For frameworks, services, and platforms that have built-in mechanisms for doing either of those, please check if there are more specific tags that can be used, and if so, add those tags as well.
For applications that are currently live in production environments, it is a common scenario that the application would need to be temporarily unavailable to end-users, because it needs to undergo maintenance activities, such as installing software updates, patching of critical bugs, replacing or restarting certain components, or cleaning-up of files/folders or data.
For such cases, it is common practice to put the application into "maintenance mode", wherein end users accessing the application would not be able to use any of the application features, and instead would see or get an "This site is under maintenance" page or response. This prevents data corruption and bad user experience, while the application is being updated.
Please make sure to also add the tags related to the framework, library, service, or platform related to the application.