• Confirmed
    • Datafixer
    • Very Important


      Maps generated in 18w31a and below reset upon updating to the latest snapshot. A new map zoomed out to the maximum based on the current location is shown.
      The correct .dat files for the map are still in the game folder.

      Analysis by BillyThePie:

      The affected snapshots are able to handle maps where 'dimension' is an integer tag. The issue only seems to occur with byte tags, which is how it was stored prior to 18w31a.

      How to reproduce

      1. Create a world (tested with 1.13)
      2. Make a few maps
      3. Update it to 20w22a
      4.  The maps don't show the original, but are reset and zoomed out


      The logs have many entries like the following that seem to be related to the problem

      (20w22a) Error: "Not a string"
      [13:29:13] [Server thread/ERROR]: Not a string
      [13:29:13] [Server thread/ERROR]: Error loading saved data: map_7
      java.lang.IllegalArgumentException: Invalid map dimension: 0b
      	at czd.c(SourceFile:127) ~[20w22a.jar:?]
      	at czd$$Lambda$4342/903822550.get(Unknown Source) ~[?:?]
      	at java.util.Optional.orElseThrow(Optional.java:290) ~[?:1.8.0_51]
      	at czd.a(SourceFile:127) ~[20w22a.jar:?]
      	at czi.c(SourceFile:72) [20w22a.jar:?]
      	at czi.b(SourceFile:58) [20w22a.jar:?]
      	at yz.a(SourceFile:1167) [20w22a.jar:?]
      	at bkc.a(SourceFile:58) [20w22a.jar:?]
      	at bkc.b(SourceFile:63) [20w22a.jar:?]
      	at yy.a(SourceFile:94) [20w22a.jar:?]
      	at yl.g(SourceFile:1070) [20w22a.jar:?]
      	at yx.p(SourceFile:398) [20w22a.jar:?]
      	at yx.a(SourceFile:337) [20w22a.jar:?]
      	at yz.a(SourceFile:348) [20w22a.jar:?]
      	at net.minecraft.server.MinecraftServer.b(SourceFile:860) [20w22a.jar:?]
      	at net.minecraft.server.MinecraftServer.a(SourceFile:799) [20w22a.jar:?]
      	at eoh.a(SourceFile:92) [20w22a.jar:?]
      	at net.minecraft.server.MinecraftServer.run(SourceFile:658) [20w22a.jar:?]
      	at java.lang.Thread.run(Thread.java:745) [?:1.8.0_51]


        1. 2020-05-24_09.51.54.png
          1.06 MB
        2. 20w20b 1.png
          20w20b 1.png
          549 kB
        3. 20w20b 2.png
          20w20b 2.png
          524 kB
        4. 20w21a 1.png
          20w21a 1.png
          578 kB
        5. 20w21a 2.png
          20w21a 2.png
          581 kB
        6. map_0.dat
          5 kB
        7. Maps (seed = 7194213826412134912).zip
          27 kB

            boq [Mojang] Bartosz Bok
            SomeRandomUser Joseph
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