diff --git a/Changelog.txt b/Changelog.txt
index 9a33c8ee2..7618395dd 100644
--- a/Changelog.txt
+++ b/Changelog.txt
@@ -1,7 +1,9 @@
 Version 2.1.210
     Fixed a memory leak involving mob metadata
+    Fixed a potential null pointer exception in InventoryListener
 
     NOTES:
+    If you're having issues with "immortal players" this is a known plugin incompatibility between mcMMO and another plugin, I need more info on what plugins need to be present to cause it. Please post info to GitHub issues or tag me on discord.
     There was a big rewrite in this update relating to how various types of metadata were being tracked/stored/retrieved
     If you run into issues with this version of mcMMO, please post about it on GitHub
 
diff --git a/pom.xml b/pom.xml
index 1484101cc..3aa6e813f 100755
--- a/pom.xml
+++ b/pom.xml
@@ -2,7 +2,7 @@
     <modelVersion>4.0.0</modelVersion>
     <groupId>com.gmail.nossr50.mcMMO</groupId>
     <artifactId>mcMMO</artifactId>
-    <version>2.1.210-SNAPSHOT</version>
+    <version>2.1.210</version>
     <name>mcMMO</name>
     <url>https://github.com/mcMMO-Dev/mcMMO</url>
     <scm>
diff --git a/src/main/java/com/gmail/nossr50/api/ExperienceAPI.java b/src/main/java/com/gmail/nossr50/api/ExperienceAPI.java
index 678f1346b..7fb2ed7ee 100644
--- a/src/main/java/com/gmail/nossr50/api/ExperienceAPI.java
+++ b/src/main/java/com/gmail/nossr50/api/ExperienceAPI.java
@@ -35,7 +35,7 @@ public final class ExperienceAPI {
      * @param skillType A string that may or may not be a skill
      * @return true if this is a valid mcMMO skill
      */
-    public static boolean isValidSkillType(String skillType) {
+    public static boolean isValidSkillType(@NotNull String skillType) {
         return mcMMO.p.getSkillTools().matchSkill(skillType) != null;
     }
 
diff --git a/src/main/java/com/gmail/nossr50/util/player/UserManager.java b/src/main/java/com/gmail/nossr50/util/player/UserManager.java
index 732840720..ef0b63e43 100644
--- a/src/main/java/com/gmail/nossr50/util/player/UserManager.java
+++ b/src/main/java/com/gmail/nossr50/util/player/UserManager.java
@@ -8,6 +8,8 @@ import org.bukkit.OfflinePlayer;
 import org.bukkit.entity.Entity;
 import org.bukkit.entity.Player;
 import org.bukkit.metadata.FixedMetadataValue;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
 import java.util.ArrayList;
 import java.util.Collection;
@@ -24,7 +26,7 @@ public final class UserManager {
      *
      * @param mcMMOPlayer the player profile to start tracking
      */
-    public static void track(McMMOPlayer mcMMOPlayer) {
+    public static void track(@NotNull McMMOPlayer mcMMOPlayer) {
         mcMMOPlayer.getPlayer().setMetadata(MetadataConstants.METADATA_KEY_PLAYER_DATA, new FixedMetadataValue(mcMMO.p, mcMMOPlayer));
 
         if(playerDataSet == null)
@@ -43,8 +45,12 @@ public final class UserManager {
      *
      * @param player The Player object
      */
-    public static void remove(Player player) {
+    public static void remove(@NotNull Player player) {
         McMMOPlayer mcMMOPlayer = getPlayer(player);
+
+        if(mcMMOPlayer == null)
+            return;
+
         mcMMOPlayer.cleanup();
         player.removeMetadata(MetadataConstants.METADATA_KEY_PLAYER_DATA, mcMMO.p);
 
@@ -91,7 +97,7 @@ public final class UserManager {
         mcMMO.p.getLogger().info("Finished save operation for "+trackedSyncData.size()+" players!");
     }
 
-    public static Collection<McMMOPlayer> getPlayers() {
+    public static @NotNull Collection<McMMOPlayer> getPlayers() {
         Collection<McMMOPlayer> playerCollection = new ArrayList<>();
 
         for (Player player : mcMMO.p.getServer().getOnlinePlayers()) {
@@ -109,11 +115,11 @@ public final class UserManager {
      * @param playerName The name of the player whose McMMOPlayer to retrieve
      * @return the player's McMMOPlayer object
      */
-    public static McMMOPlayer getPlayer(String playerName) {
+    public static @Nullable McMMOPlayer getPlayer(String playerName) {
         return retrieveMcMMOPlayer(playerName, false);
     }
 
-    public static McMMOPlayer getOfflinePlayer(OfflinePlayer player) {
+    public static @Nullable McMMOPlayer getOfflinePlayer(OfflinePlayer player) {
         if (player instanceof Player) {
             return getPlayer((Player) player);
         }
@@ -121,7 +127,7 @@ public final class UserManager {
         return retrieveMcMMOPlayer(player.getName(), true);
     }
 
-    public static McMMOPlayer getOfflinePlayer(String playerName) {
+    public static @Nullable McMMOPlayer getOfflinePlayer(String playerName) {
         return retrieveMcMMOPlayer(playerName, true);
     }
 
@@ -130,7 +136,7 @@ public final class UserManager {
      * @param player target player
      * @return McMMOPlayer object for this player, null if Player has not been loaded
      */
-    public static McMMOPlayer getPlayer(Player player) {
+    public static @Nullable McMMOPlayer getPlayer(@Nullable Player player) {
         //Avoid Array Index out of bounds
         if(player != null && player.hasMetadata(MetadataConstants.METADATA_KEY_PLAYER_DATA))
             return (McMMOPlayer) player.getMetadata(MetadataConstants.METADATA_KEY_PLAYER_DATA).get(0).value();
@@ -138,7 +144,10 @@ public final class UserManager {
             return null;
     }
 
-    private static McMMOPlayer retrieveMcMMOPlayer(String playerName, boolean offlineValid) {
+    private static @Nullable McMMOPlayer retrieveMcMMOPlayer(@Nullable String playerName, boolean offlineValid) {
+        if(playerName == null)
+            return null;
+
         Player player = mcMMO.p.getServer().getPlayerExact(playerName);
 
         if (player == null) {
@@ -152,7 +161,7 @@ public final class UserManager {
         return getPlayer(player);
     }
 
-    public static boolean hasPlayerDataKey(Entity entity) {
+    public static boolean hasPlayerDataKey(@Nullable Entity entity) {
         return entity != null && entity.hasMetadata(MetadataConstants.METADATA_KEY_PLAYER_DATA);
     }
 }
diff --git a/src/main/java/com/gmail/nossr50/util/skills/CombatUtils.java b/src/main/java/com/gmail/nossr50/util/skills/CombatUtils.java
index a855f3a4c..e576baae2 100644
--- a/src/main/java/com/gmail/nossr50/util/skills/CombatUtils.java
+++ b/src/main/java/com/gmail/nossr50/util/skills/CombatUtils.java
@@ -320,14 +320,13 @@ public final class CombatUtils {
         Entity painSource = event.getDamager();
         EntityType entityType = painSource.getType();
 
-        if (target instanceof Player) {
+        if (target instanceof Player player) {
             if(ExperienceConfig.getInstance().isNPCInteractionPrevented()) {
                 if (Misc.isNPCEntityExcludingVillagers(target)) {
                     return;
                 }
             }
 
-            Player player = (Player) target;
             if (!UserManager.hasPlayerDataKey(player)) {
                 return;
             }
@@ -738,7 +737,7 @@ public final class CombatUtils {
      * @param target The defending entity
      * @param primarySkillType The skill being used
      */
-    public static void processCombatXP(@NotNull McMMOPlayer mcMMOPlayer, LivingEntity target, PrimarySkillType primarySkillType) {
+    public static void processCombatXP(@NotNull McMMOPlayer mcMMOPlayer, @NotNull LivingEntity target, @NotNull PrimarySkillType primarySkillType) {
         processCombatXP(mcMMOPlayer, target, primarySkillType, 1.0);
     }
 
@@ -750,7 +749,7 @@ public final class CombatUtils {
      * @param primarySkillType The skill being used
      * @param multiplier final XP result will be multiplied by this
      */
-    public static void processCombatXP(@NotNull McMMOPlayer mcMMOPlayer, LivingEntity target, PrimarySkillType primarySkillType, double multiplier) {
+    public static void processCombatXP(@NotNull McMMOPlayer mcMMOPlayer, @NotNull LivingEntity target, @NotNull PrimarySkillType primarySkillType, double multiplier) {
         double baseXP = 0;
         XPGainReason xpGainReason;