I am trying to migrate over my Lightroom classic catalog to the Cloud based Lightroom version. When i start migration about a few minutes in i get an error - 'Not Enough disk space to complere migration' then told Lr needs enough space to copy videos before uploading to the cloud. Clear 500gb on Windows to enable migration... I have over a TB of storage on the LR Cloud, and my catalog saved on my external ssd. Not sure why i need additional space to clear. I am also not sure where to clear the space? On my PC or the SSD... all very confusing
I'm not going to explain this very well because I'm not a heavy user of Lightroom for the cloud. But the program needs 500 GB on your computer hard drive to prepare your LrC catalog for migration. It's part of the migration process to the cloud. After the migration is complete that 500 GB won't be needed anymore, but it has to be used for the migration process. Someone else can probably give you more information.
@JP Hess is correct, to do the migration, you require as much space on your startup disk as all your images take. The reason is that in order to migrate, Lightroom cloudy first copies all raw images into a temporary folder on your main startup disk and then slowly uploads all the images to the cloud, slowly releasing this space. Basically you will need twice the space your images already take up. If your catalog is too big to do this with the available internal hard disk space, the only thing you can do is to create smaller sub catalogs from Classic and migrate those one-by-one. It is a limitation of how Adobe designed the migration process.