Lightroom Classic 7.5: Sync Yields "bad argument #1 to '?' (number expected, got nil)" Error Messages

  • 11
  • Problem
  • Updated 2 years ago
  • Solved
  • (Edited)
Within the last several weeks, I have started to get errors when trying to sync from LR Classic.  Some problem images have been successfully synced for months, and others are new.  The problems seemed to begin when I removed some photos from All Photos in LR CC.  In the upper left corner, I see "Syncing 3 photos", though the number changes.  In Preferences, Sync Activity, the images have had the message "bad argument #1 to '?' (number expected, got nil)", and the Remove from All Synced Photos option doesn't seem to do anything.
Is there some way I can reset the sync environment?  Would that be a solution? Thanks.
Photo of Jk10003


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Posted 2 years ago

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Photo of Akshay Mathur

Akshay Mathur, Employee

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Official Response
Classic -> Preferences -> Lightroom Sync -> Press alt/option -> Rebuild Sync data . Lightroom will restart and syncing will reset and there will be no impact on your images.
Photo of HannesKa


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Akshay, do you agree that ther is a bug in LR?

I had the same problem and solved the issue:
i searched/filtered all photos in the sync-collection which have no "date"-entry (but only in a "hidden" field that is used for one filter).
in the right panel in lr-classic-cc there is a field "capture time" that is filled, you can't see the empty field in the right metadata panel in LR.

i filled the field with a date/time, then the photos were synced

the workaround is from an other user (tpnotes) who filtered and deleted this photos from the synced-collection.

see here: