same problem, l have already come across a similar problem in internet in other people, as i understood: This is not a local setup issue. The failure happens at the network level between Xcode and Apple’s MobileAsset/CDN endpoints. Until Apple fixes the MobileAsset/CDN routing (or the network path changes), affected users cannot download simulators runtimes where it appear. Or wait when they add it in catalog of assets on website for download form there, and try to install, but then i have an issue with "destination" when i want to create build by Xcode(during build i start getting error that i have. to have 26.x version, even though i have already 18.2), i tried change in "destinations" but Xcode doesn't see my simulators(based on 18.2) in catalogs, only need to install last version that Xcode offers to install(26.x), but i have 18.2 which i downloaded from catalog of assets on website I might be wrong, but that's it looks so. I can download simulator version 17.x, but not version 18.x or 26.x on Xcode 26.x. (errors the same like in author) But I can download simulator version 18.x on Xcode 16.4 on another mac.