Jumping out of gear

Graham K

When applying pressure on the pedal mainly uphills the chain jumps off the cassette, it goes each way either slipping to try and get an easier gear or jumping down onto a harder gear.
The chain and cassette are only a couple of months old, so I am presuming its an adjustment issue, would this be at the shifter end or the cassette end?

supersonic

Adjust the cable tension with the shifter or mech barrel adjuster (if you have the latter).

Assuming nothing is bent or worn, then is usually an adjustment issue. Also make sure the cables are clean and lubed.