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 following is taken from the library description.
Perhaps this is something for the NoMachine developers to investigate for future releases.
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
All existing binary executables linked against glibc's libcrypt should
work unmodified with the library supplied by this package.