Without %missingok, RPM will print confusing errors during in-place upgrades to Red Hat Enterprise Linux 9, like this: warning: file /lib64/power9/libthread_db.so.1: remove failed: No such file or directory warning: file /lib64/power9/libthread_db-1.0.so: remove failed: No such file or directory warning: file /lib64/power9/librt.so.1: remove failed: No such file or directory warning: file /lib64/power9/librt-2.33.so: remove failed: No such file or directory warning: file /lib64/power9/libpthread.so.0: remove failed: No such file or directory warning: file /lib64/power9/libpthread-2.33.so: remove failed: No such file or directory warning: file /lib64/power9/libm.so.6: remove failed: No such file or directory warning: file /lib64/power9/libm-2.33.so: remove failed: No such file or directory warning: file /lib64/power9/libc.so.6: remove failed: No such file or directory warning: file /lib64/power9/libc-2.33.so: remove failed: No such file or directory I reviewed the RPM source code and %missingok is the only way to suppress this warning.
I'm no longer sure if this worthwhile to do. We will likely have ldconfig warnings during in-place upgrades from Red Hat Enterprise Linux 8 to 9 if we install glibc's DSOs under their sonames, not versioned files (see Fedora bug 1652867). That warning won't go away because it makes sense for ldconfig in general. And if we cannot get down to zero warnings, we still need to document something, and documenting another warning isn't too much trouble.
Closing as per comment 2.