This version does not support collection view cell content view. Open this document with at least Xcode 11.0

I've read accepted answer, but it wasn't obvious where to find "property" which could be just switched off or something like.

To make it more clear: you just need to replace all occurencies of collectionViewCellContentView with view in storyboard source code. For example see screenshot:

Next, rebuild and Xcode will remove <capability name="collection view cell content view" minToolsVersion="11.0"/> requirement; or remove it manually if you're using Xcode 10.

Hope will be helpful.

EDIT

Found how to "switch off" using of collection view cell content view, but you'll still need Xcode 11 to open storyboard. Change size to Default in collection view cell prototype size inspector:

Try to open the storyboard file with a text editor and search for the property. Usually when there is a warning, Xcode will show this warning during compile time. See if double-clicking the warning redirects you to the line of code where the problem occurs.