Aktenplatz keeps a version history for every file, so the editing state stays traceable and earlier versions are never lost.
Upload a new version
When you upload a new version of an existing file, it becomes the current version; the previous one is kept as an older revision.
View & restore versions
Open Versions to see the list of all revisions. With Restore you make an older version the current one again. Prompt: "Restore this version as the current one? The current version will be preserved as an older revision." Then: "Version restored". No revision is lost in the process.
Note: versioning is enabled in the project details.