I've decided to move from LR 6 to the new LR CC, so I first upgraded to LR Classic and then downloaded LR CC and selected 'migrate catalog'
The migration was successful but there was a warning about some files not being migrated.
However, it seems that none of my photos migrated - the only ones I have in CC are the ones I'd previously uploaded to the cloud from my iPad.
I've tried the migration process again, but it just tells me that the catalog has already been migrated. All my original photos are still visible in LR Classic, but none of them appear in LR CC.
Any ideas how to try the migration process again, and what might have gone wrong?
I found the problem: it was incorrect permissions on the folder where I'd asked LR to store the local copies of images. It's a shame that it didn't fail with an informative error message.