Message to Letter error 1.5

Command line arguments: -popupwindow
UnityEngine.StackTraceUtility:ExtractStackTrace ()
Verse.Log:Message (string)
Verse.Root:CheckGlobalInit ()
Verse.Root:Start ()
Verse.Root_Entry:Start ()

RimWorld 1.5.4055 rev1156
UnityEngine.StackTraceUtility:ExtractStackTrace ()
Verse.Log:Message (string)
RimWorld.VersionControl:LogVersionNumber ()
Verse.Root:CheckGlobalInit ()
Verse.Root:Start ()
Verse.Root_Entry:Start ()

Initializing new game with mods:
  - brrainz.harmony
  - Ludeon.RimWorld
  - okthisismyidnow.Message2Letter.Specific (incompatible version)
UnityEngine.StackTraceUtility:ExtractStackTrace ()
Verse.Log:Message (string)
Verse.Game:InitNewGame ()
Verse.Root_Play/<>c:<Start>b__1_2 ()
Verse.LongEventHandler:RunEventFromAnotherThread (System.Action)
Verse.LongEventHandler/<>c:<UpdateCurrentAsynchronousEvent>b__28_0 ()
System.Threading.ThreadHelper:ThreadStart_Context (object)
System.Threading.ExecutionContext:RunInternal (System.Threading.ExecutionContext,System.Threading.ContextCallback,object,bool)
System.Threading.ExecutionContext:Run (System.Threading.ExecutionContext,System.Threading.ContextCallback,object,bool)
System.Threading.ExecutionContext:Run (System.Threading.ExecutionContext,System.Threading.ContextCallback,object)
System.Threading.ThreadHelper:ThreadStart ()

Exception updating alert RimWorld.Alert_ColonistNeedsRescuing: System.MissingMethodException: void Verse.LetterStack.ReceiveLetter(Verse.TaggedString,Verse.TaggedString,Verse.LetterDef,Verse.LookTargets,RimWorld.Faction,RimWorld.Quest,System.Collections.Generic.List`1<Verse.ThingDef>,string)
[Ref 183916]
 at Verse.Messages.AcceptsMessage (System.String text, Verse.LookTargets lookTargets) [0x000d8] in <207fb8d321f84f5ca065105bd53fb51b>:0
     - POSTFIX okthisismyidnow.Message2Letter.Specific: Void Message2Letter.Patch_Message:Postfix_1(Boolean& __result, String text, LookTargets lookTargets)
 at Verse.Messages.Message (System.String text, Verse.LookTargets lookTargets, Verse.MessageTypeDef def, System.Boolean historical) [0x00000] in <207fb8d321f84f5ca065105bd53fb51b>:0
 at RimWorld.Alert_Critical.AlertActiveUpdate () [0x00049] in <207fb8d321f84f5ca065105bd53fb51b>:0
 at RimWorld.AlertsReadout.AlertsReadoutUpdate () [0x00472] in <207fb8d321f84f5ca065105bd53fb51b>:0
UnityEngine.StackTraceUtility:ExtractStackTrace ()
Verse.Log:Error (string)
Verse.Log:ErrorOnce (string,int)
RimWorld.AlertsReadout:AlertsReadoutUpdate ()
RimWorld.UIRoot_Play:UIRootUpdate ()
Verse.Root:Update ()
Verse.Root_Play:Update ()