Currently, the default Memory Size for PMM2.2.0 OVF image is 1 GB, which is not enough to run PMM-server and also perform Upgrade, the instance runs out of memory.
For example: if we take a look at an pmm-server instance running on OVF with just one mysql instance configured to monitor this is how the memory usage looks like:
clearly there is not enough storage available to perform an upgrade for PMM-server running on this instance.
when we try to force update, using alt+click, we can see OOM error in the log:
Solution: Just increase Memory to 4GB AND add at least 1GB Swap