Lightroom Classic 15.4.1 Duplicate Detection appears to ignore duplicate photos stored on an exFAT external drive.Configuration:Windows 11 External NVMe SSD connected via Thunderbolt Drive F: formatted as exFAT Lightroom catalog functions normally Photos open, edit, and save correctly on the external driveDiagnostics performed:fsutil fsinfo volumeinfo F: reports: File System Name: exFAT Is ReadWrite chkdsk F: Completed with no file system errors. Lightroom has full access to edit and save files on the drive.Issue:The new Duplicate Detection feature reports "No Duplicates Found" even though duplicate images are known to exist on the external drive.Because the drive is confirmed to be mounted read/write and Lightroom can edit the files normally, this does not appear to be a Windows permissions issue.Could you please confirm whether Duplicate Detection in Lightroom Classic 15.4.1 fully supports image libraries stored on exFAT volumes, or whether this is a known issue requiring NTFS?Thank you,Ron

R

ron pank

Known Participant

質問

Does Lightroom Classic 15.4.1's Duplicate Detection feature fully support image libraries stored on exFAT volumes

Forum|Forum|29 days ago
June 23, 2026
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Lightroom Classic 15.4.1 Duplicate Detection appears to ignore duplicate photos stored on an exFAT external drive.

Configuration:

Windows 11
External NVMe SSD connected via Thunderbolt
Drive F: formatted as exFAT
Lightroom catalog functions normally
Photos open, edit, and save correctly on the external drive

Diagnostics performed:

fsutil fsinfo volumeinfo F: reports:
- File System Name: exFAT
- Is ReadWrite
chkdsk F: Completed with no file system errors.
Lightroom has full access to edit and save files on the drive.

Issue:
The new Duplicate Detection feature reports "No Duplicates Found" even though duplicate images are known to exist on the external drive.

Because the drive is confirmed to be mounted read/write and Lightroom can edit the files normally, this does not appear to be a Windows permissions issue.

Could you please confirm whether Duplicate Detection in Lightroom Classic 15.4.1 fully supports image libraries stored on exFAT volumes, or whether this is a known issue requiring NTFS?

Thank you,

Ron

johnrellis

Legend

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@ron pank, @Peter_Tuncurry, I did a quickie test with LR 15.4.1 / Windows 11 using a new catalog created on a USB Exfat drive, with photos freshly imported from the drive. Duplicates view correctly identified duplicates.

A next troubleshooting step would be to create a folder on the drive with a single photo duplicated in File Explorer 10 times. Import that folder into LR with the Add option. Does Duplicates view identify those 10 copies as duplicates?

KR Seals

Community Expert

As this discussion has mentioned, the duplicate process is done in the catalog, what ever that drive that is located on.

Try comparing the metadata of some files you think are exact duplicates. This means checking the time stamp down to the very second or fraction of a second.

BTW, my tests on external drives have shown that exFAT or Fat32 formatted drives run at about 1/10 the access speed of the same hardware formatted to Windows NTFS. The situation is similar on Macs, exFAT VS native Mac OS format, APFS. There are, obviously, reasons to use exFAT or FAT32 drives, but at a great performance penalty.

Ken Seals - Nikon Z 9, Z 8, 14mm-800mm. Computer Win 11 Pro, I7-14700K, 64GB, RTX3070TI. Travel machine: 2021 MacBook Pro M1 MAX 64GB. All Adobe apps.

Peter_Tuncurry

Participant

Mate, I thought it was just me.

I too am having this issue.

I might go back to storing it on my main drive. 😪

JohanElzenga

Community Expert

As far as I know the duplicate detection is done in the catalog, not by reading the images from disk. Images must be real duplicates, so for example not a series of images that are identical because they were taken from a stationary subject with the camera on a tripod.

-- Johan W. Elzenga

R

ron pank作成者

Known Participant

Duplicate works on internal drives but not on my external drive. WHY?

And I don’t kinow what you mean “not a series of images that are identical because they were taken from a stationary subject with the camera on a tripod.”

KR Seals

Community Expert

I don’t think that @JohanElzenga said that. He said the duplicate function works in the catalog (on the previews, I assume).

The time and date stamp in the image file would be an indication that the sequence of identical images taken on a tripod are not duplicates.

It’s likely that your catalog is on a fast internal drive, inferring that it’s happening on an internal drive.

Ken Seals - Nikon Z 9, Z 8, 14mm-800mm. Computer Win 11 Pro, I7-14700K, 64GB, RTX3070TI. Travel machine: 2021 MacBook Pro M1 MAX 64GB. All Adobe apps.

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