Sorry, I am not a developer or a code user, but I couldn't find help anywhere else and I hope that experienced people like you can maybe figure it out.
I don't know if "the story" matters, you can skip it if it doesn't: after I did a system restore from a Time Machine backup, updated to Catalina and then Migrating Assistant, I found out that I couldn't install apps from installers anymore (specifically, the SkyGo app...). After many tries, I came to the conclusion that the problem was a missing directory of installation, and I think the problem is in /private/tmp.
In fact, if I go in the /private folder, there is no tmp folder, if I show hidden files there is a tmp .alias file. I can't create a new tmp folder, neither delete tmp .alias.
I am using macOS Catalina 10.15.1.
I do apologize if I was not clear, I will try to give you as many extra details as you ask.
Any ideas on how to resolve this? Thank you very much!