diff --git a/src/g_level.cpp b/src/g_level.cpp
index 194ebb888..97061852e 100644
--- a/src/g_level.cpp
+++ b/src/g_level.cpp
@@ -1367,8 +1367,12 @@ void G_SerializeLevel (FArchive &arc, bool hubLoad)
 		<< level.aircontrol
 		<< level.teamdamage
 		<< level.maptime
-		<< i
-		<< level.nextmusic;
+		<< i;
+
+	if (SaveVersion >= 3313)
+	{
+		arc << level.nextmusic;
+	}
 
 	// Hub transitions must keep the current total time
 	if (!hubLoad)
diff --git a/src/g_shared/a_lightning.cpp b/src/g_shared/a_lightning.cpp
index 80e83e1e4..e7c598d3e 100644
--- a/src/g_shared/a_lightning.cpp
+++ b/src/g_shared/a_lightning.cpp
@@ -44,6 +44,26 @@ void DLightningThinker::Serialize (FArchive &arc)
 
 	arc << Stopped << NextLightningFlash << LightningFlashCount;
 
+	if (SaveVersion < 3243)
+	{ 
+		// Do nothing with old savegames and just keep whatever the constructor made
+		// but read the obsolete data from the savegame 
+		for (i = (numsectors + (numsectors+7)/8); i > 0; --i)
+		{
+			if (SaveVersion < 3223)
+			{
+				BYTE bytelight;
+				arc << bytelight;
+			}
+			else
+			{
+				short shortlight;
+				arc << shortlight;
+			}
+		}
+		return;
+	}
+
 	if (arc.IsLoading ())
 	{
 		if (LightningLightLevels != NULL)
diff --git a/src/p_acs.cpp b/src/p_acs.cpp
index 5d520ffb7..a50113782 100644
--- a/src/p_acs.cpp
+++ b/src/p_acs.cpp
@@ -2032,19 +2032,35 @@ void FBehavior::StaticStopMyScripts (AActor *actor)
 
 void P_SerializeACSScriptNumber(FArchive &arc, int &scriptnum, bool was2byte)
 {
-	arc << scriptnum;
-	// If the script number is negative, then it's really a name.
-	// So read/store the name after it.
-	if (scriptnum < 0)
+	if (SaveVersion < 3359)
 	{
-		if (arc.IsStoring())
+		if (was2byte)
 		{
-			arc.WriteName(FName(ENamedName(-scriptnum)).GetChars());
+			WORD oldver;
+			arc << oldver;
+			scriptnum = oldver;
 		}
 		else
 		{
-			const char *nam = arc.ReadName();
-			scriptnum = -FName(nam);
+			arc << scriptnum;
+		}
+	}
+	else
+	{
+		arc << scriptnum;
+		// If the script number is negative, then it's really a name.
+		// So read/store the name after it.
+		if (scriptnum < 0)
+		{
+			if (arc.IsStoring())
+			{
+				arc.WriteName(FName(ENamedName(-scriptnum)).GetChars());
+			}
+			else
+			{
+				const char *nam = arc.ReadName();
+				scriptnum = -FName(nam);
+			}
 		}
 	}
 }
diff --git a/src/p_mobj.cpp b/src/p_mobj.cpp
index 68dbf2707..3d676cddc 100644
--- a/src/p_mobj.cpp
+++ b/src/p_mobj.cpp
@@ -230,9 +230,12 @@ void AActor::Serialize (FArchive &arc)
 		<< velz
 		<< tics
 		<< state
-		<< Damage
-		<< projectileKickback
-		<< flags
+		<< Damage;
+	if (SaveVersion >= 3227)
+	{
+		arc << projectileKickback;
+	}
+	arc	<< flags
 		<< flags2
 		<< flags3
 		<< flags4
@@ -266,10 +269,12 @@ void AActor::Serialize (FArchive &arc)
 	{
 		arc << args[0];
 	}
-	arc << args[1] << args[2] << args[3] << args[4]
-		<< accuracy
-		<< stamina
-		<< goal
+	arc << args[1] << args[2] << args[3] << args[4];
+	if (SaveVersion >= 3427)
+	{
+		arc << accuracy << stamina;
+	}
+	arc << goal
 		<< waterlevel
 		<< MinMissileChance
 		<< SpawnFlags
@@ -304,10 +309,14 @@ void AActor::Serialize (FArchive &arc)
 		<< maxtargetrange
 		<< meleethreshold
 		<< meleerange
-		<< DamageType
+		<< DamageType;
+	if (SaveVersion >= 3237) 
+	{
+		arc
 		<< PainType
-		<< DeathType
-		<< gravity
+		<< DeathType;
+	}
+	arc	<< gravity
 		<< FastChaseStrafeCount
 		<< master
 		<< smokecounter
@@ -316,16 +325,22 @@ void AActor::Serialize (FArchive &arc)
 		<< VisibleToTeam // [BB]
 		<< pushfactor
 		<< Species
-		<< Score
-		<< DesignatedTeam
-		<< lastpush << lastbump
+		<< Score;
+	if (SaveVersion >= 3113)
+	{
+		arc << DesignatedTeam;
+	}
+	arc << lastpush << lastbump
 		<< PainThreshold
 		<< DamageFactor
 		<< WeaveIndexXY << WeaveIndexZ
 		<< PoisonDamageReceived << PoisonDurationReceived << PoisonPeriodReceived << Poisoner
-		<< PoisonDamage << PoisonDuration << PoisonPeriod
-		<< PoisonDamageType << PoisonDamageTypeReceived
-		<< ConversationRoot << Conversation;
+		<< PoisonDamage << PoisonDuration << PoisonPeriod;
+	if (SaveVersion >= 3235)
+	{
+		arc << PoisonDamageType << PoisonDamageTypeReceived;
+	}
+	arc << ConversationRoot << Conversation;
 
 	{
 		FString tagstr;
diff --git a/src/p_saveg.cpp b/src/p_saveg.cpp
index adadbac95..3b7533efc 100644
--- a/src/p_saveg.cpp
+++ b/src/p_saveg.cpp
@@ -326,9 +326,18 @@ void P_SerializeWorld (FArchive &arc)
 	for (i = 0, sec = sectors; i < numsectors; i++, sec++)
 	{
 		arc << sec->floorplane
-			<< sec->ceilingplane
-			<< sec->lightlevel
-			<< sec->special
+			<< sec->ceilingplane;
+		if (SaveVersion < 3223)
+		{
+			BYTE bytelight;
+			arc << bytelight;
+			sec->lightlevel = bytelight;
+		}
+		else
+		{
+			arc << sec->lightlevel;
+		}
+		arc << sec->special
 			<< sec->tag
 			<< sec->soundtraversed
 			<< sec->seqType
diff --git a/src/p_spec.cpp b/src/p_spec.cpp
index e1777cf46..a41fa2cad 100644
--- a/src/p_spec.cpp
+++ b/src/p_spec.cpp
@@ -727,7 +727,17 @@ IMPLEMENT_CLASS (DLightTransfer)
 void DLightTransfer::Serialize (FArchive &arc)
 {
 	Super::Serialize (arc);
-	arc << LastLight << Source << TargetTag << CopyFloor;
+	if (SaveVersion < 3223)
+	{
+		BYTE bytelight;
+		arc << bytelight;
+		LastLight = bytelight;
+	}
+	else
+	{
+		arc << LastLight;
+	}
+	arc << Source << TargetTag << CopyFloor;
 }
 
 DLightTransfer::DLightTransfer (sector_t *srcSec, int target, bool copyFloor)
@@ -810,7 +820,17 @@ IMPLEMENT_CLASS (DWallLightTransfer)
 void DWallLightTransfer::Serialize (FArchive &arc)
 {
 	Super::Serialize (arc);
-	arc << LastLight << Source << TargetID << Flags;
+	if (SaveVersion < 3223)
+	{
+		BYTE bytelight;
+		arc << bytelight;
+		LastLight = bytelight;
+	}
+	else
+	{
+		arc << LastLight;
+	}
+	arc << Source << TargetID << Flags;
 }
 
 DWallLightTransfer::DWallLightTransfer (sector_t *srcSec, int target, BYTE flags)
diff --git a/src/p_user.cpp b/src/p_user.cpp
index 955003937..de48cf20b 100644
--- a/src/p_user.cpp
+++ b/src/p_user.cpp
@@ -2613,8 +2613,18 @@ void player_t::Serialize (FArchive &arc)
 		<< BlendR
 		<< BlendG
 		<< BlendB
-		<< BlendA
-		<< LogText
+		<< BlendA;
+	if (SaveVersion < 3427)
+	{
+		WORD oldaccuracy, oldstamina;
+		arc << oldaccuracy << oldstamina;
+		if (mo != NULL)
+		{
+			mo->accuracy = oldaccuracy;
+			mo->stamina = oldstamina;
+		}
+	}
+	arc << LogText
 		<< ConversationNPC
 		<< ConversationPC
 		<< ConversationNPCAngle
diff --git a/src/version.h b/src/version.h
index 524f494d7..ab877820d 100644
--- a/src/version.h
+++ b/src/version.h
@@ -75,7 +75,7 @@
 // SAVESIG should match SAVEVER.
 
 // MINSAVEVER is the minimum level snapshot version that can be loaded.
-#define MINSAVEVER 3427
+#define MINSAVEVER 3100
 
 #if SVN_REVISION_NUMBER < MINSAVEVER
 // If we don't know the current revision write something very high to ensure that