I'm up around 3tb I recommend that you use Windows File Explore to show what files, folders, etc are in the hard drive, and specifically the LrC is in. Have the file extensions shown (not hidden) have the file and folder sizes shown. Take a screenshot if that and post in a reply. This so other members can get an idea on what is going on. Some suspicions, and some items to see if they exist: Backup folder in wrong hard drive, that is on same drive as working catalog. Old backups that might no longer be helpful (you would need to look/decide) Several old catalogs that are from previous versions if LrC, before upgrades. Library preview folder for old unused catalogs (see above) Also, in case it is in a different drive or other media, where do you keep your original photos? Remember that Adobe does not recommend, nor support placing the LrC catalog on a network share, be that an actual Server, a NAS, or the Cloud. Some try this, but eventually the catalog gets corrupted. Also note that while Adobe does state they support placing the photos on the Cloud, in troubleshooting documents, they contradict that and state that is problematic. Some have luck. Also one wrinkle with OneDrive (yes I know, off topic, sort of). Some have automatic sync/copy with OneDrive in place for their catalog.Typically due to Microsoft trying to force use of MS accounts instead of local. Disable that, it eventually fouls up. If your Library path includes the words OneDrive in it, fix that. 'Some links on not putting catalog on network share: https://helpx.adobe.com/lightroom-classic/kb/catalog-faq-lightroom.html Some links on space: https://mastering-lightroom.com/lightroom-space-part-1/ https://mastering-lightroom.com/lightroom-space-part-2/
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