20w15a shows error when starting server

When I start my server I get an error message, but from playing it does nothing.
[20:38:14] [Server thread/ERROR]: Couldn't parse loot table as:random_pose
t: Non [a-z0-9/._-] character in path of location: minecraft:generic.attackDamage
at ts.<init>(SourceFile:38) ~[server.jar:?]
at ts.<init>(SourceFile:43) ~[server.jar:?]
at daa$b.a(SourceFile:185) ~[server.jar:?]
at daa$d.a(SourceFile:134) ~[server.jar:?]
at daa$d.b(SourceFile:112) ~[server.jar:?]
at czw$c.a(SourceFile:104) ~[server.jar:?]
at czw$c.b(SourceFile:89) ~[server.jar:?]
at czy$a.a(SourceFile:93) ~[server.jar:?]
at czy$a.deserialize(SourceFile:81) ~[server.jar:?]
at com.google.gson.internal.bind.TreeTypeAdapter.read(TreeTypeAdapter.java:69) ~[server.jar:?]
at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.read(TypeAdapterRuntimeTypeWrapper.java:41) ~[server.jar:?]
at com.google.gson.internal.bind.ArrayTypeAdapter.read(ArrayTypeAdapter.java:72) ~[server.jar:?]
at com.google.gson.Gson.fromJson(Gson.java:887) ~[server.jar:?]
at com.google.gson.Gson.fromJson(Gson.java:952) ~[server.jar:?]
at com.google.gson.internal.bind.TreeTypeAdapter$GsonContextImpl.deserialize(TreeTypeAdapter.java:162) ~[server.jar:?]
at acv.a(SourceFile:440) ~[server.jar:?]
at acv.a(SourceFile:456) ~[server.jar:?]
at czg$e.a(SourceFile:154) ~[server.jar:?]
at czg$e.b(SourceFile:130) ~[server.jar:?]
at czd$a.a(SourceFile:53) ~[server.jar:?]
at czd$a.deserialize(SourceFile:41) ~[server.jar:?]
at com.google.gson.internal.bind.TreeTypeAdapter.read(TreeTypeAdapter.java:69) ~[server.jar:?]
at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.read(TypeAdapterRuntimeTypeWrapper.java:41) ~[server.jar:?]
at com.google.gson.internal.bind.ArrayTypeAdapter.read(ArrayTypeAdapter.java:72) ~[server.jar:?]
at com.google.gson.Gson.fromJson(Gson.java:887) ~[server.jar:?]
at com.google.gson.Gson.fromJson(Gson.java:952) ~[server.jar:?]
at com.google.gson.internal.bind.TreeTypeAdapter$GsonContextImpl.deserialize(TreeTypeAdapter.java:162) ~[server.jar:?]
at acv.a(SourceFile:440) ~[server.jar:?]
at acv.a(SourceFile:448) ~[server.jar:?]
at cyo$b.a(SourceFile:169) ~[server.jar:?]
at cyo$b.deserialize(SourceFile:165) ~[server.jar:?]
at com.google.gson.internal.bind.TreeTypeAdapter.read(TreeTypeAdapter.java:69) ~[server.jar:?]
at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.read(TypeAdapterRuntimeTypeWrapper.java:41) ~[server.jar:?]
at com.google.gson.internal.bind.ArrayTypeAdapter.read(ArrayTypeAdapter.java:72) ~[server.jar:?]
at com.google.gson.Gson.fromJson(Gson.java:887) ~[server.jar:?]
at com.google.gson.Gson.fromJson(Gson.java:952) ~[server.jar:?]
at com.google.gson.internal.bind.TreeTypeAdapter$GsonContextImpl.deserialize(TreeTypeAdapter.java:162) ~[server.jar:?]
at acv.a(SourceFile:440) ~[server.jar:?]
at acv.a(SourceFile:456) ~[server.jar:?]
at cyp$b.a(SourceFile:213) ~[server.jar:?]
at cyp$b.deserialize(SourceFile:209) ~[server.jar:?]
at com.google.gson.internal.bind.TreeTypeAdapter.read(TreeTypeAdapter.java:69) ~[server.jar:?]
at com.google.gson.Gson.fromJson(Gson.java:887) ~[server.jar:?]
at com.google.gson.Gson.fromJson(Gson.java:952) ~[server.jar:?]
at com.google.gson.Gson.fromJson(Gson.java:925) ~[server.jar:?]
at cyq.a(SourceFile:63) ~[server.jar:?]
at java.util.HashMap.forEach(Unknown Source) ~[?:1.8.0_241]
at cyq.a(SourceFile:61) ~[server.jar:?]
at cyq.a(SourceFile:25) ~[server.jar:?]
at aam.a(SourceFile:13) ~[server.jar:?]
at java.util.concurrent.CompletableFuture.uniAccept(Unknown Source) ~[?:1.8.0_241]
at java.util.concurrent.CompletableFuture$UniAccept.tryFire(Unknown Source) ~[?:1.8.0_241]
at java.util.concurrent.CompletableFuture$Completion.run(Unknown Source) ~[?:1.8.0_241]
at aan.a(SourceFile:71) ~[server.jar:?]
at uh.run(SourceFile:18) [server.jar:?]
at ale.c(SourceFile:144) [server.jar:?]
at ali.c(SourceFile:23) [server.jar:?]
at net.minecraft.server.MinecraftServer.b(SourceFile:741) [server.jar:?]
at net.minecraft.server.MinecraftServer.c(SourceFile:140) [server.jar:?]
at ale.x(SourceFile:118) [server.jar:?]
at net.minecraft.server.MinecraftServer.bc(SourceFile:723) [server.jar:?]
at net.minecraft.server.MinecraftServer.x(SourceFile:717) [server.jar:?]
at ale.c(SourceFile:127) [server.jar:?]
at net.minecraft.server.MinecraftServer.b(SourceFile:1482) [server.jar:?]
at net.minecraft.server.MinecraftServer.a(SourceFile:465) [server.jar:?]
at net.minecraft.server.MinecraftServer.a(SourceFile:379) [server.jar:?]
at xl.d(SourceFile:217) [server.jar:?]
at net.minecraft.server.MinecraftServer.run(SourceFile:625) [server.jar:?]
at java.lang.Thread.run(Unknown Source) [?:1.8.0_241]
[20:38:14] [Server thread/WARN]: Found validation problem in {minecraft:entities/ender_dragon}.pools[0].entries[0]: Unknown loot table called minecraft:entities/reference/extra/ender_dragon