Error

Exception while saving RimWorld.Planet.WorldGrid: System.OutOfMemoryException: Out of memory
  at (wrapper managed-to-native) object:__icall_wrapper_mono_string_alloc (intptr)
  at (wrapper managed-to-native) string:InternalAllocateStr (int)
  at System.Text.StringBuilder..ctor (System.String value, Int32 startIndex, Int32 length, Int32 capacity, Int32 maxCapacity) [0x00000] in <filename unknown>:0
  at System.Text.StringBuilder..ctor (System.String value, Int32 startIndex, Int32 length, Int32 capacity) [0x00000] in <filename unknown>:0
  at System.Text.StringBuilder..ctor (Int32 capacity) [0x00000] in <filename unknown>:0
  at Verse.DataExposeUtility.AddLineBreaksToLongString (System.String str) [0x00000] in <filename unknown>:0
  at Verse.DataExposeUtility.ByteArray (System.Byte[]& arr, System.String label) [0x00000] in <filename unknown>:0
  at RimWorld.Planet.WorldGrid.ExposeData () [0x00000] in <filename unknown>:0
  at Verse.Scribe_Deep.Look[WorldGrid] (RimWorld.Planet.WorldGrid& target, Boolean saveDestroyedThings, System.String label, System.Object[] ctorArgs) [0x00000] in <filename unknown>:0
Verse.Log:Error(String)
Verse.Scribe_Deep:Look(WorldGrid&, Boolean, String, Object[])
Verse.Scribe_Deep:Look(WorldGrid&, String, Object[])
RimWorld.Planet.World:ExposeData()
Verse.Scribe_Deep:Look(World&, Boolean, String, Object[])
Verse.Scribe_Deep:Look(World&, String, Object[])
Verse.Game:ExposeData()
Verse.Scribe_Deep:Look(Game&, Boolean, String, Object[])
Verse.Scribe_Deep:Look(Game&, String, Object[])
Verse.GameDataSaveLoader:<SaveGame>m__0()
Verse.SafeSaver:DoSave(String, String, Action)
Verse.SafeSaver:Save(String, String, Action)
Verse.GameDataSaveLoader:SaveGame(String)
RimWorld.Autosaver:DoAutosave()
Verse.LongEventHandler:UpdateCurrentSynchronousEvent(Boolean&)
Verse.LongEventHandler:LongEventsUpdate(Boolean&)
Verse.Root:Update_Patch1(Object)
Verse.Root_Play:Update()