I have an existing vm instance to which I'm trying to attach a new persistent disk as detailed here Adding or Resizing Persistent Disks.
Every time I try, I receive the error detailed in the title, with no further explanation. This happen on an instance with no disk other than the boot one, but the same happens for all my 6 instances, even on instances where I have attached successfully 1 or 2 persistent disks before. Furthermore, I have an existing instance that is identical to this new one and to which I successfully attached a persistent disk, exactly as I'm trying to do now.
So it looks like something has changed in my project (as hinted by the error) but I cannot think of any action I have done that may have caused it. Does anyone know what this error means? There is no trace of it on the google support / documentation pages