KopiaUI 0.15.0 size estimation on Win11 incorrect due to hidden/system files

I have installed KopiaUI 0.15.0 on a Windows 11 notebook which has two external harddisks attached. There are two snapshots defined, one for the user profile data (with a few exclusions, cache files etc) and one for one of the external drives. (The other one will follow soon.) The backup target is a WebDAV share.

I have the impression that when KopiaUI estimates the backup / snapshot size, it does not take into account hidden and system files (like “$RECYCLE.BIN” and “System Volume Information” on Windows), even if they would be get backed up.

Is this correct?

Snapshotting files on the mentioned external USB drive will cause KopiaUI to estimate the total size to be 13GB, but in fact it was close to 28GB, because the user had a huge amount of files in their Recycle Bin. After adding “$RECYCLE.BIN” to the exclude list and snapshotting again, Kopia - again incorrectly - estimated the total backup size to be 28GB, but only backed up about 13 GB.

Am I doing something wrong, did I misunderstand something, or did I actually find a bug?


this is a bug i guess. I noticed it too while creating a snaphot. The estimation is inaccurate.