I've just experienced that sometimes RandomCycle uses a groupname, instead of a mapname, I can replicate the error easily enough by using
sm_umc_randcycle_picknextmapnow.
Output
Code:
L 11/06/2012 - 14:45:10: [umc-randomcycle.smx] User Console<0><Console><Console> requested a random map be selected now.
L 11/06/2012 - 14:45:10: [umc-randomcycle.smx] Attempting to set the next map to a random selection.
CModelLoader::Map_IsValid: No such map 'maps/Halloween / Full Moon.bsp'
L 11/06/2012 - 14:45:10: [umc-core.smx] SETMAP: Map Halloween / Full Moon is invalid!
Here it has chosen a group called "Halloween / Full Moon", instead of a map from the group.
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