Loss of Lr / folder / collection synchronisation with iMac and Lr v12 upgrades

[Tim Grant-Skardon]

I have just had my iMac upgraded with a SSD drive and additional memory.  During this process Lr v12 was installed and the Lr cache was set to the residual flash drive on the original Fusion Drive of the iMac.  When I got it home, I opened Lr Classic and the Folder structure and collections were an very old version of the structure, with many folders and photos showing as missing.  This did not reflect the Lr v11 catalogue or my folders / collections prior topugrade.  After reading around I could only find one possible solution and that was to synchronise the folders with the new catalogue.  This required a re-import of the folders and many photos.  This was successful but although the photos retained my Lr edits the Develop history was lost (it just showed the new import date).  Is there a way to rectify this and get back to my original folders and collections along with the Develop history of the files?  I am not confident enough to roll back to the earlier version of Lightroom / uninstall v12 and reinstall v11 nor to just try .loading the last Catalogue.  Any thoughts?

[JohanElzenga]

You chose the wrong 'solution'. What you need to do is open the original version 11 catalog. Lightroom Classic creates an upgraded copy when it upgrades the catalog, so the original catalog is untouched and should still be where it always was. Let Lightroom Classic upgrade a copy again.

[Tim Grant-Skardon]

Thanks Johan.  I had a feeling I would have chosen the wrong solution.  That's why I was avoiding doing anything else.  So, given wheer I now have got to what is my best way forward?  Should I adjust 'Preferences' default catalogue to start up using a previous catalogue (I assume I just search for the previpuls Lrcat v11).  Will then then automatically update to v12 and use that last correct catalogue as the basis?   Or do I need to use CC App / Lightroom Classic / ... / Other Versions  and then either 'Uninstall Lightroom Classic (12.1) or do I just 'Install Lightroom Classic (11.5) (which is the last pre-v12 version I have?  Should I delete all of the v12 files that have been created e.g. 'Lightroom Catalogue-v12.Lrcat' and its associated 'data' 'Sync.Lrdata' etc files?

[JohanElzenga · Accepted solution]

There is no reason to uninstall Lightroom and reinstall it if you have version 12.1 right now. Just launch it, use the 'Open Catalog' menu, navigate to the old version 11 catalog and open it. Lightroom Classic will show you the upgrade catalog dialog, because it can't open an older version catalog without upgrading it. Choose a new name for the upgraded catalog in the dialog and that's it. From now on use this catalog and you should be fine. You can then delete the previous V12 catalog files, just to avoid confusion.

[Tim Grant-Skardon]

Johan,

You are a star!  Thank you so much.  That worked a treat and I am now back up and running where I need to be.  Thank you.  A very Happy Christmas and new year to you.