Several times now, probably half a dozen or so, I have attempted to download Catalina. However, every time it only downloads just over 4GB of 8.09GB before returning the error message below. I have tried downloading via my own ISP and via the FON network in case it was a provider problem.

I am UK based.

The error message reads: A server with the specified hostname could not be found. An error occurred while installing the selected updates.

Can anyone help me get over this and download the whole upgrade? Is there another server to which I can go rather than the one to which Software Update automatically connects?

If it helps, the specification of the machine that I have is:

macOS Mojave v10.14.6 (18G103)
iMac (Retina 5K, 27-inch, 2017)
3.8 GHz Intel Core i5
64 GB (at the ime of this post 32GB free)2400 MHz DDR4
Radeon Pro 580 8 GB
2TB HD (1 TB free)

Incidentally, I do have "Automatically keep my Mac up to date" checked in Software Update and yet it seems to have failed to download Catalina in the background as it suggests in the Apple Support pages and I have run both TechTool pro and Disk Utility to make sure my HD is "healthy".


iMac (Retina 5K, 27-inch, 2017); 3.8 GHz Intel Core i5; 2TB HD; 64 GB 2400 MHz DDR4 RAM; Radeon Pro 580 8 GB. iPad Pro 10.5" Model MPME2B/A with 512GB capacity; iPhone SE 2020 256GB