Faction Bases Not Appearing During Attack

[Squidward Tortellini]

So recently I decided to attempt to attack a nearby Federation base, but when my forces got there, no base was generated and the game said all the forces were defeated immediately. I do not have any idea what is causing this. I do have this error though:

Error while resolving symbol "factionBase" with params=rect=(110,103,146,140), faction=Tactical Unit Delta, custom=null, ancientTempleEntranceHeight=null, pawnGroupMakerParams=null, pawnGroupKindDef=null, roofDef=null, noRoof=null, addRoomCenterToRootsToUnfog=null, singleThingToSpawn=null, singleThingDef=null, singleThingStuff=null, singleThingStackCount=null, skipSingleThingIfHasToWipeBuildingOrDoesntFit=null, singlePawnToSpawn=null, singlePawnKindDef=null, disableSinglePawn=null, singlePawnLord=null, singlePawnSpawnCellExtraPredicate=null, singlePawnGenerationRequest=null, postThingSpawn=null, postThingGenerate=null, mechanoidsCount=null, hivesCount=null, disableHives=null, thingRot=null, wallStuff=null, chanceToSkipWallBlock=null, floorDef=null, chanceToSkipFloor=null, filthDef=null, filthDensity=null, clearEdificeOnly=null, clearFillageOnly=null, clearRoof=null, ancientCryptosleepCasketGroupID=null, podContentsType=null, itemCollectionGeneratorDef=null, itemCollectionGeneratorParams=null, stockpileConcreteContents=null, stockpileMarketValue=null, innerStockpileSize=null, edgeDefenseWidth=null, edgeDefenseTurretsCount=null, edgeDefenseMortarsCount=null, edgeDefenseGuardsCount=null, mortarDef=null, pathwayFloorDef=null, cultivatedPlantDef=null, fillWithThingsPadding=null, factionBasePawnGroupPointsFactor=null, streetHorizontal=null, edgeThingAvoidOtherEdgeThings=null, allowPlacementOffEdge=null, thrustAxis=null

Exception: System.MissingMethodException: Method not found: 'RimWorld.FactionManager.RandomEnemyFaction'.
at (wrapper dynamic-method) RimWorld.BaseGen.SymbolResolver_FactionBase.Resolve_Patch1 (object,RimWorld.BaseGen.ResolveParams) <0x000fe>
at RimWorld.BaseGen.BaseGen.Resolve (Verse.Pair`2<string, RimWorld.BaseGen.ResolveParams>) <0x002ea>
at RimWorld.BaseGen.BaseGen.Generate () <0x002d9>

Verse.Log:Error(String)
RimWorld.BaseGen.BaseGen:Generate()
RimWorld.GenStep_FactionBase:ScatterAt(IntVec3, Map, Int32)
Verse.GenStep_Scatterer:Generate(Map)
Verse.MapGenerator:GenerateContentsIntoMap(IEnumerable`1, Map)
Verse.MapGenerator:GenerateMap(IntVec3, MapParent, MapGeneratorDef, IEnumerable`1, Action`1)
Verse.GetOrGenerateMapUtility:GetOrGenerateMap(Int32, IntVec3, WorldObjectDef)
Verse.GetOrGenerateMapUtility:GetOrGenerateMap(Int32, WorldObjectDef)
RimWorld.Planet.CaravanArrivalAction_AttackSettlement:DoArrivalAction(Caravan)
RimWorld.Planet.<Arrived>c__AnonStorey0:<>m__0()
Verse.LongEventHandler:UpdateCurrentSynchronousEvent(Boolean&)
Verse.LongEventHandler:LongEventsUpdate(Boolean&)
Verse.Root:Update_Patch1(Object)
Verse.Root_Play:Update()