Error System.Char[]

It started right after the last patch.

[D] 18:19:19 - Spell(string spellName): spellName=Invisibility, Id found: 66, Name found: Invisibility, NameInGame found: Invisibility, know = True

[D] 18:19:19 - Spell(string spellName): spellName=Summon Water Elemental, Id found: 31687, Name found: Summon Water Elemental, NameInGame found: Summon Water Elemental, know = True

18:19:19 - Select zone: Grizzly Hills

18:19:19 - Start Grinder Complete

[D] 18:19:19 - Spell(string spellName): spellName=Summon Water Elementa => Failed

[N] 18:19:20 - Download map "Northrend\Northrend_39_18.mesh.gz"

18:19:20 - Trial finish, close bot.

[E] 18:19:20 - System.Char[]

18:19:20 - Stop Grinder Complete

18:19:21 - Stop Grinder Complete

18:19:21 - Dispose Grinder Complete