1.21.9, the release of The Copper Age, is a game drop for Java Edition released on September 30, 2025. It adds copper tools and armor, copper golems, various copper blocks and items, shelves, and new options for the debug screen. Full changelog: https://minecraft.wiki/Java_Edition_1.21.9

Fixed

• Adjusted the timing of the new drag-to-pin interaction cue for better reliability. (Bug 1989344)

• Fixed an issue that prevented some extensions from updating via the Add-ons Manager. (Bug 1984724)

• Fixed a regression that prevented Firefox View sections from collapsing/expanding as expected. (Bug 1989200)

• Addressed a WebExtensions storage issue that could cause Firefox to crash on startup with certain extensions installed. (Bug 1989840)

• Fixed an issue where opening an add-on's "Extension settings" from the post-install prompt could break the Customize tab and some keyboard shortcuts until restart. (Bug 1983869)

• Reduced long delays when loading certain websites while connected to networks that block UDP connections. (Bug 1980812)

• Various stability and security fixes.

• Reference link to 143.0.1 release notes.

+ Italian, Russian translations update
+ Windows: tweak the ads height for avoiding too big ads in when the window is maximized
+ Android: Migrate to Material Design 3 (thanks to cjee21)
+ ADM: Dolby E profile for emission conformance checker
+ AAC: show when PNS is ued
+ MPEG-TS: map message_id code to the stored message character string
+ AC-4: Enhancement to Presentation Role display
+ AC-4: Add Bitstream level and Presentation level
+ MXF: support of experimental ARRI ULs
+ WavPack: fix duration for long duration
+ WAV: detection of C2PA + display of thumbnails characteristics
+ MasteringDisplay_Luminance: split Min and Max
+ Dolby Vision: Fill colour, transfer & matrix for profile 5 (thanks to cjee21)
+ JPEG: Detect lossless (thanks to cjee21)
+ MPEG-TS: update DVB descriptors and service types for NGVC and NGA (thanks to paulhiggs)
+ Reset MXF status based on footer partition (thanks to ammonriley)
+ VP9: VP9 in MP4 support (thanks to cjee21)
+ SphericalVideo: use StereoMode instead of of SourceCount
+ I2400, Fix crashes with some malformed files
x Android GUI: fix some display issues with the billing and preference windows
x MaxCLL/MaxFALL: value without unit in the XML/JSON output
x Fix infinite loop in UTF8 (e.g. JavaScript) build
x HDR: fix random crash with multiple HDR formats
x PAC: Fix duration/timestamps
x Spherical Video 2 support, fix BF4 support with 0.32 readout, update

• read-only demo server at https://a.ocv.me/pub/demo/
• docker image ╱ similar software ╱ client testbed

there is a discord server with an @everyone in case of future important updates, such as vulnerabilities (most recently 2025-09-07)

recent important news

• v1.19.8 (2025-09-07) fixed CVE-2025-58753 (a missing permission-check inside single-file shares)
• v1.15.0 (2024-09-08) changed upload deduplication to be default-disabled
• v1.14.3 (2024-08-30) fixed a bug that was introduced in v1.13.8 (2024-08-13); this bug could lead to data loss -- see the v1.14.3 release-notes for details

🧪 new features

• #184 add various human-readable formats for filesizes 234edde
• search for files by their identifier ("wark"/checksum) 4e38e40
  • and those are displayed in file-listings now too 456addf
• PUT-upload with header Replace will overwrite any existing files 397ed56
• xbu/xau hooks can reject uploads with a custom message df0fa9d
• #855 mDNS options to change the announced http/https port a3d9506
• #473 #383 custom favicons per-volume (.ico/png/gif/svg) 470b504
  • doesn't seem to work in internet explorer... ah whatever, go next

🩹 bugfixes

• #849 create IdP-db for --idp-store when necessary 80ca785
• #859 cbz-thumbnailing had an accidental dependency on FFmpeg 983865d
• docs: misleading markdown-expansion example e187df2

🔧 other changes

• #851 show a huge warning when copyparty accidentally detects a failing HDD and/or filesystem-corruption during indexing 6912e86 eb5d767
• #870 improved discord video embeds (thx @tsuza!) f0ecb08
• #858 prefer reflinks (not hardlinks) in the -ss security option 57650a2
• improved controlpanel action-buttons layout 9f46e4d

🌠 fun facts

• includes (a tiny bit of) code written at koie ramen
• according to Biltema, september is an excellent time to start decorating for xmas

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⚠️ not the latest version!