[Observium] Server error while clicking on ports.

Hi I was running observium successfully since last one year. Recently i migrated my running setup to new server, everything works fine except when i click on ports and inventory options from menu i get server error. I have checked apache log but nothing found except message "File does not exist: /opt/observium/html/favicon.ico"

Any clue how can i figure out what went wrong?

Thanks in advance.