Missing photos after updatte

[belcamp george]

The last upgrade for Lightroom Classic lost all of my photos and started out with an instruction to start importing. Several hours later all my photos were back (I think) but all collections were wiped out. Please please Adobe if you are going to do something like that for an upgrade please submit a warning.. I have been using lightroom since it first came out and have never seen anything like this. Please someone explain. 

I have windows 11 on a new desktop

[GoldingD]

Sounds like LrC failed to upgrade the correct catalog. Search your computer for the correct catalog, double click on the file to launch LrC.

[Rob_Cullen]

This happened to me also! (Going v11> v12) My working catalog was on a D:drive and LrC could not find it and so tried to create a new empty Catalog on C:drive.

Your new catalog will not have any editing or work!

Find your correct working catalog, as advised by @GoldingD and [Double-Click] to open it, which will then ask you to upgrade this 'correct' catalog.

When you have your old catalog working correctly, you can Delete that new catalog that has no edits or collections.

[Abambo]

When you have your old catalog working correctly, you can Delete that new catalog that has no edits or collections.

By @Rob_Cullen

It is mandatory to delete the newly created catalog structure, to avoid later confusion. Best is to note down the location of that catalog.