We have 3 instances on a server (default + 2 named), 1 of the named instances ends with this error. Googling learns me a lot on solutions, less so on causes. Strangely though, when I open SSMS I see the same version number for this faulty instance as for the other instances, for which the SP3 installation completed succesfully. Some superfluous checking shows things seem to work fine on this faulty instance.
Obviously I worry and am not happy with this faulty result. I wonder though if this error really indicates an error? I have seen other errors in the MS environment, which were not really errors, just a (sub)system encountering a situation it could not handle properly and thus shooting off a (random) error message.
So, is this a serious error or not?