Cannot mix incompatible Qt library

Lately I am constantly getting this error when running some Qt software.

Cannot mix incompatible Qt library (5.15.7) with this library (5.15.9)

There are several issues on github about it but they’ve been closed:

There is also a topic here that has no replies:

The solutions generally involve finding old packages and removing them. This makes me question everything I thought I knew about nix. I thought one of the main features of nix packages was that you could run multiple versions of the same package. I generally don’t even “install” packages but run them using “nix run”. I’ve ran the garbage collector even though I shouldn’t have to and that still doesn’t fix this problem. I don’t have this problem with anything else other than Qt packages. It seems weird and very wrong that adding something to my nix store could break something else that was working fine before. It seems like that these types of packages should be flagged or something. Can someone please help me understand why this happens and if there is a workaround other than going on a wild goose chase trying to find packages to remove? Thanks.

Cannot mix incompatible Qt library (5.15.10) with this library (5.15.9)

I’m also getting this with the current “unstable” packages. I haven’t found any way around it yet… :slightly_frowning_face:
I was running Qt Creator and Clion in a nix-shell with the Qt dev packages.