I think I have found the solution. During the installation of the new version of Rserve, there was an unnoticed error message:
This was because the previous version of Rserve was running. The solution is this:
0. sudo yum install openssl-devel
1. sudo killall -INT Rserve
2. sudo mount -o remount,exec /tmp
3. sudo R
install.packages('Rserve',,"http://rforge.net/",type="source")
4. sudo mount -o remount,noexec /tmp
5. sudo systemctl start rserve