This file is almost never present on standard end-user systems, so the kernel logs a "failed to load" error (-2) when it can't find it.
iwlwifi: failed to load firmware iwlwifi: iwldebug-yoyobin-exclusive iwlwifi firmware failed to load iwldebugyoyobin exclusive
Prevention and best practices
If you want to stop this warning from appearing in your boot logs, you can disable the initialization debugging feature in the iwlwifi module: This file is almost never present on standard