Player Data Failed to be Saved!!

Hello I got this error on my server. Player lose their progress because of this error.

Sorry for my bad english. I'm new to this stuff so I don't really know how to fix it.



Code:
at java.lang.Thread.run(Thread.java:831) [?:?]
[14:42:21 ERROR]: Failed to save player data for Subiira
net.minecraft.server.v1_16_R3.ReportedException: Saving entity NBT
at net.minecraft.server.v1_16_R3.E https://1921681001.id/ ntity.save(Entity.java:1777) ~[patched_1.16.5.jar:git-Paper-775]
at net.minecraft.server.v1_16_R3.WorldN https://19216811.cam/ BTStorage.save(WorldNBTStorage.java:37) ~[patched_1.16.5.jar:git-Paper-775]
at net.minecraft.server.v1_16_R3.PlayerList.savePlayerFile(PlayerList.java:570) ~[patched_1.16.5.jar:git-Paper-775]
at net.minecraft.server.v1_16_R3.PlayerList.disconnect(PlayerList.java:621) ~[patched_1.16.5.jar:git-Paper-775]
at net.minecraft.server.v1_16_R3.PlayerConnection.a(PlayerConnection.java:1856) ~[patched_1.16.5.jar:git-Paper-775]
at net.minecraft.server.v1_16_R3.NetworkManager.handleDisconnection(NetworkManager.java:520) ~[patched_1.16.5.jar:git-Paper-775]
at net.minecraft.server.v1_16_R3.ServerConnection.c(ServerConnection.java:188) ~[patched_1.16.5.jar:git-Paper-775]
at net.minecraft.server.v1_16_R3.MinecraftServer.b(MinecraftServer.java:1515) ~[patched_1.16.5.jar:git-Paper-775]
at net.minecraft.server.v1_16_R3.DedicatedServer.b(DedicatedServer.java:436) ~[patched_1.16.5.jar:git-Paper-775]
at net.minecraft.server.v1_16_R3.MinecraftServer.a(MinecraftServer.java:1342) ~[patched_1.16.5.jar:git-Paper-775]
at net.minecraft.server.v1_16_R3.MinecraftServer.w(MinecraftServer.java:1130) ~[patched_1.16.5.jar:git-Paper-775]
at net.minecraft.server.v1_16_R3.MinecraftServer.lambda$a$0(MinecraftServer.java:291) ~[patched_1.16.5.jar:git-Paper-775]
at java.lang.Thread.run(Thread.java:831) [?:?]
Caused by: java.lang.NullPointerException: Cannot invoke "org.bukkit.World.getUID()" because the return value of "org.bukkit.Location.getWorld()" is null
at net.minecraft.server.v1_16_R3.Entity.save(Entity.java:1757) ~[patched_1.16.5.jar:git-Paper-775]
... 12 more
Caused by: java.lang.NullPointerException: Cannot invoke "org.bukkit.World.getUID()