The upgrade from Fedora 29 to 30 requires that the package libxcrypt-compat be installed for NoMachine v6.6.8_5_x86_64 to function properly. The package is available in the normal F30 repository.
The following is taken from the library description.
This package contains the library providing the compatibility API for applications that are linked against glibc’s libxcrypt, or that are still using the unsafe and deprecated, encrypt, encrypt_r, setkey, setkey_r, and fcrypt functions, which are still required by recent versions of POSIX, the Single UNIX Specification, and various other standards. All existing binary executables linked against glibc’s libcrypt should work unmodified with the library supplied by this package.