tested? no

code/modules/client/preferences_savefile.dm

@@ -211,23 +211,27 @@ SAVEFILE UPDATING/VERSIONING - 'Simplified', or rather, more coder-friendly ~Car
 
 /datum/preferences/proc/load_preferences()
 	if(!path)
-		return 0
+		return FALSE
 	if(world.time < loadprefcooldown)
 		if(istype(parent))
 			to_chat(parent, "<span class='warning'>You're attempting to load your preferences a little too fast. Wait half a second, then try again.</span>")
-		return 0
+		return FALSE
 	loadprefcooldown = world.time + PREF_SAVELOAD_COOLDOWN
 	if(!fexists(path))
-		return 0
+		return FALSE
 
 	var/savefile/S = new /savefile(path)
 	if(!S)
-		return 0
+		return FALSE
 	S.cd = "/"
 
 	var/needs_update = savefile_needs_update(S)
 	if(needs_update == -2)		//fatal, can't load any data
-		return 0
+		var/bacpath = "[path].updatebac" //todo: if the savefile version is higher then the server, check the backup, and give the player a prompt to load the backup
+		if (fexists(bacpath))
+			fdel(bacpath) //only keep 1 version of backup
+		fcopy(S, bacpath) //byond helpfully lets you use a savefile for the first arg.
+		return FALSE
 
 	. = TRUE
 
@@ -289,8 +293,14 @@ SAVEFILE UPDATING/VERSIONING - 'Simplified', or rather, more coder-friendly ~Car
 
 	//try to fix any outdated data if necessary
 	if(needs_update >= 0)
+		var/bacpath = "[path].updatebac" //todo: if the savefile version is higher then the server, check the backup, and give the player a prompt to load the backup
+		if (fexists(bacpath))
+			fdel(bacpath) //only keep 1 version of backup
+		fcopy(S, bacpath) //byond helpfully lets you use a savefile for the first arg.
 		update_preferences(needs_update, S)		//needs_update = savefile_version if we need an update (positive integer)
 
+
+
 	//Sanitize
 	ooccolor		= sanitize_ooccolor(sanitize_hexcolor(ooccolor, 6, 1, initial(ooccolor)))
 	lastchangelog	= sanitize_text(lastchangelog, initial(lastchangelog))
@@ -332,7 +342,25 @@ SAVEFILE UPDATING/VERSIONING - 'Simplified', or rather, more coder-friendly ~Car
 
 	verify_keybindings_valid()		// one of these days this will runtime and you'll be glad that i put it in a different proc so no one gets their saves wiped
 
-	return 1
+	if(needs_update >= 0) //save the updated version
+		var/old_default_slot = default_slot
+		var/old_max_save_slots = max_save_slots
+
+		for (var/slot in S.dir) //but first, update all current character slots.
+			if (copytext(slot, 1, 10) != "character")
+				continue
+			var/slotnum = text2num(copytext(slot, 10))
+			if (!slotnum)
+				continue
+			max_save_slots = max(max_save_slots, slotnum) //so we can still update byond member slots after they lose memeber status
+			default_slot = slotnum
+			if (load_character()) // this updtates char slots
+				save_character()
+		default_slot = old_default_slot
+		max_save_slots = old_max_save_slots
+		save_preferences()
+
+	return TRUE
 
 /datum/preferences/proc/verify_keybindings_valid()
 	// Sanitize the actual keybinds to make sure they exist.
@@ -422,17 +450,17 @@ SAVEFILE UPDATING/VERSIONING - 'Simplified', or rather, more coder-friendly ~Car
 
 /datum/preferences/proc/load_character(slot)
 	if(!path)
-		return 0
+		return FALSE
 	if(world.time < loadcharcooldown) //This is before the check to see if the filepath exists to ensure that BYOND can't get hung up on read attempts when the hard drive is a little slow
 		if(istype(parent))
 			to_chat(parent, "<span class='warning'>You're attempting to load your character a little too fast. Wait half a second, then try again.</span>")
 		return "SLOW THE FUCK DOWN" //the reason this isn't null is to make sure that people don't have their character slots overridden by random chars if they accidentally double-click a slot
 	loadcharcooldown = world.time + PREF_SAVELOAD_COOLDOWN
 	if(!fexists(path))
-		return 0
+		return FALSE
 	var/savefile/S = new /savefile(path)
 	if(!S)
-		return 0
+		return FALSE
 	S.cd = "/"
 	if(!slot)
 		slot = default_slot
@@ -444,7 +472,7 @@ SAVEFILE UPDATING/VERSIONING - 'Simplified', or rather, more coder-friendly ~Car
 	S.cd = "/character[slot]"
 	var/needs_update = savefile_needs_update(S)
 	if(needs_update == -2)		//fatal, can't load any data
-		return 0
+		return FALSE
 
 	. = TRUE
 
@@ -462,7 +490,7 @@ SAVEFILE UPDATING/VERSIONING - 'Simplified', or rather, more coder-friendly ~Car
 			pref_species = new newtype
 
 
-		scars_index = rand(1,5)
+	scars_index = rand(1,5) // WHY
 
 	//Character
 	S["real_name"]				>> real_name
@@ -616,6 +644,7 @@ SAVEFILE UPDATING/VERSIONING - 'Simplified', or rather, more coder-friendly ~Car
 			gear_points -= init_cost
 
 	//try to fix any outdated data if necessary
+	//preference updating will handle saving the updated data for us.
 	if(needs_update >= 0)
 		update_character(needs_update, S)		//needs_update == savefile_version if we need an update (positive integer)