This VIDEO showing how to correctly update and upgrade your existing EVE VM to the newest version.
Shortly:
Connect to your EVE server on CLI as root and type following commands: ( update from V76 to V77 )
apt-get update
apt-get upgrade
Clear your browser cache...
SPECIAL NOTES: ( update from V71 or lower to V2.0.3-77 )
Stop all labs
Use the command :
/opt/unetlab/wrappers/unl_wrapper -a stopall
apt-get update
apt-get dist-upgradeFinally reboot server