what is multigrid residual?

[camelluxin]

Running 11.8, I encounter a warning:
################################################################################
# WARNING                                                                      #
#                                                                              #
# The computed multigrid residual is greater than the required accuracy.       #
#                                                                              #
# Computed residual :   8.88278e-006                                            #
# Required accuracy :   1.00000e-009                                            #
#                                                                              #
################################################################################

What is the multigrid residual and how to set it?
Nothing happened when I run the same program by 11.2.
 

[Anders Blom]

Shouldn't really be something to worry about, but if you want to send use the system, we can have a look, and see if there is reason for concern.

We changed the multigrid method in 11.8, so that would explain the lack of message in 11.2.