NetworkManager.service: Failed with result 'exit-code'.
システムログを見ると、
NetworkManager[5822]: /usr/sbin/NetworkManager: relocation error: /lib/x86_64-linux-gnu/libcurl-gnutls.so.4: symbol gnutls_srp_allocate_client_credentials version GNUTLS_3_4 not defined in file libgnutls.so.30 with link time reference