Unable to resize Azure VM in Classic Portal

I’ve run into this error a couple of times now, when trying to resize Azure VM’s:

The current deployment cannot be updated with the API version specified. This is because the current deployment contains multiple virtual IPs created with a newer version of the service management API.

So, my Cloud Service has multiple public IP addresses, and therefore I cannot resize the VM. Makes sense, no?

After some tests, I tried the same action from the new Azure portal – https://portal.azure.com:

And guess what it worked! Now it makes sense! No, not really.

Just out of curiosity I tried doing it from the Classic portal again, but no luck. Do I need to say how much I want to migrate to ARM, like NOW?! 🙂