default/linux/amd64/17.1/no-multilib The amd64 17.1 profiles switch to a more standard 'no SYMLINK_LIB' multilib layout, and require an explicit migration. The migration is performed using the app-portage/unsymlink-lib tool. The following steps can be used to upgrade your system: 1. Sync and upgrade your system to the newest package versions to reduce the risk of issues. 2. Install the tool: # emerge -1v app-portage/unsymlink-lib 3. Run 'unsymlink-lib --analyze' and check the output for obvious mistakes. If you need to perform any changes to the system, remember to run 'unsymlink-lib --analyze' again afterwards. [past this point do not call emerge or modify /usr manually] 4. This is a very good time to make a backup. 5. Run 'unsymlink-lib --migrate'. You can add '--pretend' first to see what is going to happen. 6. Reboot your system. Check if important programs work. In particular, verify that e.g. 'emerge --info' works (but do not install anything). If you hit any serious problems, you can use 'unsymlink-lib --rollback' to revert the changes and return to step 3. 7. Run 'unsymlink-lib --finish'. You can add '--pretend' first to see what is going to happen but note that you're going to see a very long list of files to remove. 8. Switch the profile, e.g.: # eselect profile set default/linux/amd64/17.1/desktop [at this point you can start using emerge again. emerge will then not display this message anymore, but the remaining steps are still required!] 9. Rebuild gcc: # emerge -1v sys-devel/gcc:9.3.0 [ repeat for other slots you will be using ] 10. If you are using a multilib profile, rebuild all 32-bit packages. This can be done using: # emerge -1v --deep /lib32 /usr/lib32 /usr/lib/llvm/*/lib32 11. Once the last 32-bit package is rebuilt, your package manager should remove the orphaned /lib32 and /usr/lib32 symlinks. If that does not happen, remove them manually: # rm /lib32 /usr/lib32 For known issues, please see bug #506276 [1]. If you have any problems with the new profiles or the migration procedure, please report a bug and make it block the tracker. [1] https://bugs.gentoo.org/506276