On Tue, May 14, 2013 at 08:35:23AM +0200, Ian Hinder wrote:

 (line 1698 of /work/00915/hinder/Cactus/AEI/arrangements/Carpet/CarpetInterp/src/interp.cc):
 -> Grid function "AHFINDERDIRECT::ahmask" has only 1 active time levels on refinement level 1; this is not enough for time interpolation

Does anyone know why this happens

Something tries to interpolate the mask. Evolution shouldn't do that,
the mask is supposed to be written each (sub-)timestep AFAIR. Now, there
are other possibilities, as you mentioned below...

and if there is a workaround I can use to get the run going again?

The questions is what makes Carpet interpolate, and avoid that.

I have ADMBase::metric_timelevels set to the default, which is 1.
Should it be 3?

It should work with 1.

How about changing the frequency of AHFinderDirect output to match
the coarsest timelevel?

I suspect that this is the cause of your problem: you output in between
evolution times of the coarsest level, making Carpet interpolate the
mask. You could (only for the mask probably), output only at full
coarse level steps, if don't need it more often. You could also try
(although here I am less sure that this will prevent interpolation) to
restrict the output of the mask to some of the finer levels only, at
full time steps of these.