1. A computer-implemented method for updating an application that contains metadata, comprising the steps of: while running an original version of the application prior to running an updated version of the application, performing: labeling metadata in the original version of the application with a first version identifier; making a copy of the original version of the application; wherein the copy of the original version of the application contains the metadata as labeled with the first version identifier and as said metadata existed when the copy of the original version of the application was made; installing an update to the copy of the original version of the application to generate the updated version of the application, wherein installing the update includes modifying the metadata in the copy of the original version of the application while installing the update to the copy of the original version of the application, allowing one or more users to continue modifying the metadata in the original version of the application, and determining periodically whether installing the update to the updated version of the application has been completed, and in response to a determination that installing the update to the updated version of the application has not been completed, performing: labeling the metadata in the original version of the application with another version identifier; determining a first difference between the metadata labeled with the another version identifier in the original version of the application and metadata most recently labeled with a most recent another version identifier; updating the metadata in the updated version of the application to incorporate the first difference; after making the metadata in the original version of the application read-only, labeling the metadata in the original version of the application with a new version identifier; determining a second difference between the metadata labeled with the new version identifier and the metadata in the original version labeled with the most recent another version identifier; updating the metadata in the updated version of the application to incorporate the second difference.