All command blocks lose all nbt data on update to 18w20a
See title, the log writes the following:
[17:14:50] [Server thread/ERROR]: Failed to load data for block entity minecraft:command_block
com.google.gson.JsonSyntaxException: com.google.gson.stream.MalformedJsonException: Use JsonReader.setLenient(true) to accept malformed JSON at line 1 column 1 path $
at com.google.gson.internal.Streams.parse(Streams.java:60) ~[minecraft_server.jar:?]
at com.google.gson.internal.bind.TreeTypeAdapter.read(TreeTypeAdapter.java:65) ~[minecraft_server.jar:?]
at wq.a(SourceFile:493) ~[minecraft_server.jar:?]
at wq.a(SourceFile:518) ~[minecraft_server.jar:?]
at ic$a.a(SourceFile:243) ~[minecraft_server.jar:?]
at bam.b(SourceFile:69) ~[minecraft_server.jar:?]
at bmj.b(SourceFile:45) ~[minecraft_server.jar:?]
at bmf.c(SourceFile:78) [minecraft_server.jar:?]
at bqb.a(SourceFile:496) [minecraft_server.jar:?]
at bqb.a(SourceFile:101) [minecraft_server.jar:?]
at si.g(SourceFile:94) [minecraft_server.jar:?]
at si.b(SourceFile:118) [minecraft_server.jar:?]
at si.a(SourceFile:160) [minecraft_server.jar:?]
at net.minecraft.server.MinecraftServer.g_(SourceFile:384) [minecraft_server.jar:?]
at net.minecraft.server.MinecraftServer.a(SourceFile:336) [minecraft_server.jar:?]
at ru.d(SourceFile:248) [minecraft_server.jar:?]
at net.minecraft.server.MinecraftServer.run(SourceFile:497) [minecraft_server.jar:?]
at java.lang.Thread.run(Unknown Source) [?:1.8.0_161]
Caused by: com.google.gson.stream.MalformedJsonException: Use JsonReader.setLenient(true) to accept malformed JSON at line 1 column 1 path $
at com.google.gson.stream.JsonReader.syntaxError(JsonReader.java:1559) ~[minecraft_server.jar:?]
at com.google.gson.stream.JsonReader.checkLenient(JsonReader.java:1401) ~[minecraft_server.jar:?]
at com.google.gson.stream.JsonReader.doPeek(JsonReader.java:593) ~[minecraft_server.jar:?]
at com.google.gson.stream.JsonReader.peek(JsonReader.java:425) ~[minecraft_server.jar:?]
at com.google.gson.internal.Streams.parse(Streams.java:46) ~[minecraft_server.jar:?]
... 17 more
Linked Issues
is duplicated by5
Created Issue:
Impulse command blocks lose all nbt data on update to 18w20a
See title, the log writes the following:
[17:14:50] [Server thread/ERROR]: Failed to load data for block entity minecraft:command_block com.google.gson.JsonSyntaxException: com.google.gson.stream.MalformedJsonException: Use JsonReader.setLenient(true) to accept malformed JSON at line 1 column 1 path $ at com.google.gson.internal.Streams.parse(Streams.java:60) ~[minecraft_server.jar:?] at com.google.gson.internal.bind.TreeTypeAdapter.read(TreeTypeAdapter.java:65) ~[minecraft_server.jar:?] at wq.a(SourceFile:493) ~[minecraft_server.jar:?] at wq.a(SourceFile:518) ~[minecraft_server.jar:?] at ic$a.a(SourceFile:243) ~[minecraft_server.jar:?] at bam.b(SourceFile:69) ~[minecraft_server.jar:?] at bmj.b(SourceFile:45) ~[minecraft_server.jar:?] at bmf.c(SourceFile:78) [minecraft_server.jar:?] at bqb.a(SourceFile:496) [minecraft_server.jar:?] at bqb.a(SourceFile:101) [minecraft_server.jar:?] at si.g(SourceFile:94) [minecraft_server.jar:?] at si.b(SourceFile:118) [minecraft_server.jar:?] at si.a(SourceFile:160) [minecraft_server.jar:?] at net.minecraft.server.MinecraftServer.g_(SourceFile:384) [minecraft_server.jar:?] at net.minecraft.server.MinecraftServer.a(SourceFile:336) [minecraft_server.jar:?] at ru.d(SourceFile:248) [minecraft_server.jar:?] at net.minecraft.server.MinecraftServer.run(SourceFile:497) [minecraft_server.jar:?] at java.lang.Thread.run(Unknown Source) [?:1.8.0_161] Caused by: com.google.gson.stream.MalformedJsonException: Use JsonReader.setLenient(true) to accept malformed JSON at line 1 column 1 path $ at com.google.gson.stream.JsonReader.syntaxError(JsonReader.java:1559) ~[minecraft_server.jar:?] at com.google.gson.stream.JsonReader.checkLenient(JsonReader.java:1401) ~[minecraft_server.jar:?] at com.google.gson.stream.JsonReader.doPeek(JsonReader.java:593) ~[minecraft_server.jar:?] at com.google.gson.stream.JsonReader.peek(JsonReader.java:425) ~[minecraft_server.jar:?] at com.google.gson.internal.Streams.parse(Streams.java:46) ~[minecraft_server.jar:?] ... 17 more
Changed Summary:
Impulsecommand blocks lose all nbt data on update to 18w20aAll command blocks lose all nbt data on update to 18w20a
Added Attachments:
Added Attachments:
Added Linked Issues:
is duplicated by
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Deleted Comment:
Not only commandblocks have this problem.
minecraft:structures/ruin/big_mossy_8.nbt an some blocks more have this problem an crash the Server.
See my log:[^2018-05-15-6.log] an crashreport: [^crash-2018-05-15_19.12.06-server.txt]
Removed Attachments:
Added Assignee:
[Mojang] Georgii Gavrichev
Added Linked Issues:
is duplicated by
Added Linked Issues:
is duplicated by





It's the same things for chain and repeating command block, all of the commands inside disappear when I update my map in 18w20a :/
Confirmed and attached screenshot
It looks like all command block data is wiped due to a com.google.gson.JsonSyntaxException, which is visible in the log files:

I even thought to myself to back up my world and boom, all command block data is gone... ;_;
*EDIT:* Whoops, didn't read everything in the description
I made a CMD block mod in 17w19b, luckily I made a backup...
One of my command blocks (it was a NBT CB containing a command for a 1.13 snapshot) I had in my saved toolbars and placed in a 1.12.2 world kept its command upon loading it, but all others (ICB, CCB and RCB with a simpl3 "say test" command) were wiped.
Not the same issue.