Might be off topic, but this is the closest thread that I found related to my problem. For people running into this issue still, I initially only set [.allowReadWrite] as availablePermission on the UICloudSharingController. Because of this I couldn't invite people over the UICloudSharingController. Adding the .allowPrivate permission fixed this, ending up with: [.allowReadWrite, .allowPrivate]. Hope this helps.

What helped for me was in Xcode going to "Settings" > "Accounts" > "Click the associated account" > "Click Manage Certificates". Once I did this, the crashes loaded properly again without crashes.