diff --git a/Plan/bungeecord/src/main/java/com/djrapitops/plan/system/listeners/bungee/PlayerOnlineListener.java b/Plan/bungeecord/src/main/java/com/djrapitops/plan/system/listeners/bungee/PlayerOnlineListener.java
index d39cd9c8e..e59e35351 100644
--- a/Plan/bungeecord/src/main/java/com/djrapitops/plan/system/listeners/bungee/PlayerOnlineListener.java
+++ b/Plan/bungeecord/src/main/java/com/djrapitops/plan/system/listeners/bungee/PlayerOnlineListener.java
@@ -78,7 +78,7 @@ public class PlayerOnlineListener implements Listener {
             InetAddress address = player.getAddress().getAddress();
             long time = System.currentTimeMillis();
 
-            sessionCache.cacheSession(uuid, new Session(uuid, serverInfo.getServerUUID(), time, "", ""));
+            sessionCache.cacheSession(uuid, new Session(uuid, serverInfo.getServerUUID(), time, null, null));
 
             boolean gatheringGeolocations = config.isTrue(DataGatheringSettings.GEOLOCATIONS);
 
@@ -114,7 +114,7 @@ public class PlayerOnlineListener implements Listener {
 
             long time = System.currentTimeMillis();
             // Replaces the current session in the cache.
-            sessionCache.cacheSession(uuid, new Session(uuid, serverInfo.getServerUUID(), time, "", ""));
+            sessionCache.cacheSession(uuid, new Session(uuid, serverInfo.getServerUUID(), time, null, null));
             processing.submit(processors.info().playerPageUpdateProcessor(uuid));
         } catch (Exception e) {
             errorHandler.log(L.WARN, this.getClass(), e);
diff --git a/Plan/common/src/main/java/com/djrapitops/plan/data/time/WorldTimes.java b/Plan/common/src/main/java/com/djrapitops/plan/data/time/WorldTimes.java
index 1ecc3b809..0424be87e 100644
--- a/Plan/common/src/main/java/com/djrapitops/plan/data/time/WorldTimes.java
+++ b/Plan/common/src/main/java/com/djrapitops/plan/data/time/WorldTimes.java
@@ -55,6 +55,7 @@ public class WorldTimes {
     }
 
     private void addWorld(String worldName, String gameMode, long changeTime) {
+        if (worldName == null || gameMode == null) return;
         times.put(worldName, new GMTimes(gameMode, changeTime));
     }
 
diff --git a/Plan/common/src/main/java/com/djrapitops/plan/system/settings/config/WorldAliasSettings.java b/Plan/common/src/main/java/com/djrapitops/plan/system/settings/config/WorldAliasSettings.java
index 5206f0f95..866af95c2 100644
--- a/Plan/common/src/main/java/com/djrapitops/plan/system/settings/config/WorldAliasSettings.java
+++ b/Plan/common/src/main/java/com/djrapitops/plan/system/settings/config/WorldAliasSettings.java
@@ -85,6 +85,8 @@ public class WorldAliasSettings {
      * @param world World name
      */
     public void addWorld(String world) {
+        Verify.isFalse(Verify.isEmpty(world), () -> new IllegalArgumentException("Attempted to save a world alias '" + world + "'"));
+
         ConfigNode aliasSect = getAliasSection();
 
         String previousValue = aliasSect.getString(world);
@@ -165,7 +167,7 @@ public class WorldAliasSettings {
         }
         WorldTimes worldTimes = session.getUnsafe(SessionKeys.WORLD_TIMES);
         if (!session.supports(SessionKeys.END)) {
-            return "Current: " + aliases.get(worldTimes.getCurrentWorld());
+            return "Current: " + aliases.getOrDefault(worldTimes.getCurrentWorld(), "Unknown");
         }
 
         Map<String, Long> playtimePerAlias = getPlaytimePerAlias(worldTimes);
diff --git a/Plan/common/src/main/resources/bungeeconfig.yml b/Plan/common/src/main/resources/bungeeconfig.yml
index c439053fb..d5d2c4385 100644
--- a/Plan/common/src/main/resources/bungeeconfig.yml
+++ b/Plan/common/src/main/resources/bungeeconfig.yml
@@ -139,6 +139,11 @@ Formatting:
     NoSeconds: 'MMM d YYYY, HH:mm'
     JustClock: 'HH:mm:ss'
 # -----------------------------------------------------
+# World aliases can be used to rename worlds and to combine multiple worlds into a group.
+# -----------------------------------------------------
+World_aliases:
+  world: world
+# -----------------------------------------------------
 # These settings will make Plan write .js, .css, .json and .html files to some location on disk.
 # Relative path will render to /plugins/Plan/path
 # Make sure user running the server has write permissions to the path.
diff --git a/Plan/velocity/src/main/java/com/djrapitops/plan/system/listeners/velocity/PlayerOnlineListener.java b/Plan/velocity/src/main/java/com/djrapitops/plan/system/listeners/velocity/PlayerOnlineListener.java
index e96dbf447..9019379bf 100644
--- a/Plan/velocity/src/main/java/com/djrapitops/plan/system/listeners/velocity/PlayerOnlineListener.java
+++ b/Plan/velocity/src/main/java/com/djrapitops/plan/system/listeners/velocity/PlayerOnlineListener.java
@@ -81,7 +81,7 @@ public class PlayerOnlineListener {
             InetAddress address = player.getRemoteAddress().getAddress();
             long time = System.currentTimeMillis();
 
-            sessionCache.cacheSession(uuid, new Session(uuid, serverInfo.getServerUUID(), time, "", ""));
+            sessionCache.cacheSession(uuid, new Session(uuid, serverInfo.getServerUUID(), time, null, null));
 
             boolean gatheringGeolocations = config.isTrue(DataGatheringSettings.GEOLOCATIONS);
 
@@ -117,7 +117,7 @@ public class PlayerOnlineListener {
 
             long now = System.currentTimeMillis();
             // Replaces the current session in the cache.
-            sessionCache.cacheSession(uuid, new Session(uuid, serverInfo.getServerUUID(), now, "", ""));
+            sessionCache.cacheSession(uuid, new Session(uuid, serverInfo.getServerUUID(), now, null, null));
             processing.submit(processors.info().playerPageUpdateProcessor(uuid));
         } catch (Exception e) {
             errorHandler.log(L.WARN, this.getClass(), e);