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Cleanroom Relauncher
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Cleanroom Relauncher

by Cleanroom • Downloads: 0 • Followers: 0
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Cleanroom Relauncher

Relaunches a Forge 1.12.2 instance with Cleanroom.

Client only at the moment.

  • Relaunch Now installs the latest Cleanroom and a compatible Java runtime.
  • Advanced Settings lets you pick a version, a Java install, and JVM flags.
  • Settings can still be changed later in-game via the config menu.

Installation Notes

  • Keep the ! at the start of the filename so Forge loads the mod first.
  • Cleanroom also expects Fugue to fix some of the old Forge mods.
    • And Scalar for mods that used to depend on Scala 2 components.
  • Releases are taken from GitHub, with CleanroomMC Maven as a fallback.
  • Downloads and provisioned Java are cached under ~/.cleanroom/ (relauncher/ and java/).
    • Change that parent directory with -Dcleanroom.homeDir=<path>.

Distribution via Modpacks

  • Put the jar in mods/. Players see the setup window on first launch.
    • To skip that window, ship a filled-in config/relauncher.json. Run the pack once locally and copy the file.
    • Automatic Java setup is the usual choice for distribution.
  • If the instance is already running Cleanroom, nothing is relaunched.

Config

Written to config/relauncher.json:

  • Cleanroom Version
  • Automatic Java (version + vendor, default Java 25 / Zulu) or a path to an executable
  • Extra JVM Arguments
  • Whether to check for newer Cleanroom releases
  • Cleanups

Links

All Versions

+ Add Version
Name Game version Platforms Published Downloads Actions
1.12.2
Forge
4d ago 1
1.12.2
Forge
11d ago 1
1.12.2
Forge
13d ago 1
1.12.2
Forge
15d ago 1
1.12.2
Forge
16d ago 1
1.12.2
Forge
2mo ago 1
1.12.2
Forge
2mo ago 1
1.12.2
Forge
2mo ago 1
1.12.2
Forge
2mo ago 1
1.12.2
Forge
2mo ago 1
1.12.2
Forge
3mo ago 1
1.12.2
Forge
3mo ago 1
1.12.2
Forge
3mo ago 1
1.12.2
Forge
3mo ago 1
1.12.2
Forge
3mo ago 1
1.12.2
Forge
4mo ago 1
1.12.2
Forge
4mo ago 1
1.12.2
Forge
4mo ago 1
1.12.2
Forge
6mo ago 1
1.12.2
Forge
7mo ago 1
1.12.2
Forge
11mo ago 1
1.12.2
Forge
last yr. 1
1.12.2
Forge
last yr. 1
1.12.2
Forge
last yr. 1
1.12.2
Forge
last yr. 1
1.12.2
Forge
last yr. 1
1.12.2
Forge
last yr. 1
1.12.2
Forge
last yr. 1
1.12.2
Forge
last yr. 1
1.12.2
Forge
last yr. 1
1.12.2
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last yr. 1
1.12.2
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last yr. 1
1.12.2
Forge
last yr. 1
🖼️

No gallery images uploaded.

### Changed
  • Fetch Cleanroom releases from CleanroomMC's Maven first, with GitHub as the fallback
  • Java arguments now support multiple whitespace, quotes and escape characters
  • Removed eMudhra's emSign root CAs from the bundled CA certs used on Java 8u101 and older, following their distrust after the eMudhra key compromise

### Fixed
  • Crash with No Cleanroom releases are available to relaunch with. when GitHub returns an empty release list
  • An empty cached release list no longer persists, it is fetched again on the next launch
  • accessToken is no longer printed in the relauncher's debug log
  • Loading popups no longer flash briefly on later launches when nothing needs downloading

[1.2.1] 1.2.1 by Cleanroom on Oct 15, 2026
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### Changed

  • Use the same User-Agent across the board for downloads, fixes issue with recent updates to Cloudflare's Browser Integrity Checks

[1.2.0] 1.2.0 by Cleanroom on Oct 13, 2026
Download
### Added

  • Support for Cleanroom 0.7.x releases and its new MultiMC pack layout

### Fixed

  • Crash with NoSuchFileException: /patches/net.minecraft.json when relaunching into a 0.7.x release

[1.1.6] 1.1.6 by Cleanroom on Oct 11, 2026
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### Fixed

  • Files being re-downloaded on every launch when they do not come with a comparable hash or algorithm

[1.1.5] 1.1.5 by Cleanroom on Oct 10, 2026
Download
### Changed

  • Downloads now time out per file (10 seconds to connect, 30 seconds to read) and retry up to 3 times, replacing the overall 3 minutes cap

### Fixed

  • Interrupted or truncated Java downloads leaving behind a broken install that gets picked up on later launches
  • Java provisioning downloading builds for the wrong architecture, operating system or C library (musl/glibc)
  • Provisioned Java installs nested inside Cleanroom's home directory not being detected

[1.1.4] 1.1.4 by Cleanroom on Sep 08, 2026
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### Changed

  • Capped 3 minutes timeout on fetching versions and downloading

[1.1.3] 1.1.3 by Cleanroom on Aug 28, 2026
Download
### Fixed

  • Issue with transitive dependencies causing crash

[1.1.2] 1.1.2 by Cleanroom on Aug 23, 2026
Download
### Fixed

  • Logic concerning whether to notify the user of the latest Cleanroom release

[1.1.1] 1.1.1 by Cleanroom on Aug 20, 2026
Download
### Added

  • Ability to change Cleanroom's home directory (where Relauncher & Java provisioning caches data) via cleanroom.homeDir property

[1.0.5] 1.0.5 by Cleanroom on Aug 14, 2026
Download
### Fixed

  • Extraction of installations in older macOS's failing

[1.0.3] 1.0.3 by Cleanroom on Aug 09, 2026
Download
### Fixed

  • Scaling issues on X11 compositing environments

[1.0.2] 1.0.2 by Cleanroom on Aug 04, 2026
Download
### Fixed

  • GUI not working properly on certain Linux compositors

### Changed

  • Better sensitivity on certain scrollbars
  • Disabled resizing

[1.0.1] 1.0.1 by Cleanroom on Jul 27, 2026
Download
### Added

  • More robust way of checking for fonts to use

### Fixed

  • Some instances where text isn't being rendered on the UI

[1.0.0] 1.0.0 by Cleanroom on Jul 25, 2026
Download
### Added

  • Dark Theme

### Changed

  • Menu, to be "modern" with inclusion of rounded corners, pill buttons
  • More readable and softer font selection
  • Better scaling
  • Removed duplicate UI code

### Fixed

  • Arguments list not responding properly if checkboxes are ticked/unticked
  • Errors not handled properly pertaining reading of configuration
  • Taskbar window previews not working

[0.6.3] 0.6.3 by Cleanroom on Jul 15, 2026
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### Fixed

  • Errors when parsing installations

[0.6.2] 0.6.2 by Cleanroom on Jul 05, 2026
Download
### Fixed

  • Duplicate downloads as the downloader is now cleaned up to avoid this from happening

[0.6.1] 0.6.1 by Cleanroom on Jul 01, 2026
Download
### Changed

  • Stopped shading in com.google.code.gson in relauncher
  • Shade in org.apache.commons.compress version 1.28.0 to avoid issues

[0.6.0] 0.6.0 by Cleanroom on Jun 30, 2026
Download
### Added

  • Download hash validation for Cleanroom packs and libraries
  • Configuration options to clear the relauncher cache folder and provisioned Java folder
  • Option to disable querying GitHub for release updates

### Fixed

  • Incompatibility with new file names
  • Update notification behavior to avoid redundant prompts
  • Redundant release/config save calls during relaunch setup
  • Temurin vendor matching/internal naming

### Changed

  • Reworked Java provisioning to use JavaUtils's provisioning APIs
  • Improved cache deletion by walking files safely before removal
  • Added network timeouts and request headers when querying GitHub releases

### Added

  • Notification Screen
  • Update Screen

### Changed

  • Conform to CF standards

### Added
  • Auto-provisioning of Java installations
  • In-game configuration menu (accessed through the mod menu)

### Changed
  • Settings GUI to look a little better
  • First-time users normally interacts with the GUI before relaunching, though now it may be skipped if Automatic Install options are filled, for modpack distribution purposes
### Fixed
  • Issues with file paths on some systems and locales
  • Stop scanning the entirety of /opt on Linux (updated JavaUtils to 1.1.5)
### Added
  • Respect the launcher's original heap space setting arguments (-Xms, -Xmx) if none is specified in the configuration

### Fixed
  • Compatibility with newer MMC pack formats (starting from Cleanroom 0.3.19)
  • Encode and decode configuration with UTF-8
  • Some Linux installs not being detected properly (updated JavaUtils to 1.1.3)

### Changed
  • Thanks to @ZZZank, using MethodHandles to call the wrapper class's main method instead of standard reflection, allows for a cleaner stacktrace
### Added
  • 1hr time-to-live for cached releases, this should be temporary and a better solution may come

### Fixed
  • Arguments being piped into relaunched process
  • Improved performance with wrapper, as it triggered Windows Defender and hiked CPU percentage

### Changed
  • Added exclamation mark at the beginning of file for Forge to load relauncher's coremod earlier
  • Simplified checking and replacing of wrapper classes if it ever updates

### Fixed
  • Arguments not being passed to the relaunching process properly (thanks to @PrototypeTrousers for the fix)
### Fixed
  • Arguments being left out of the relaunching process
### Fixed
  • Fix some Java installs not being detected properly on non-Windows systems

### Changed
  • Updated JavaUtils
### Fixed
  • Edge-case when creating file when parent directory may not exist
### Fixed
  • Some java paths not being properly recognized and parsed

### Changed
  • Updated JavaUtils
### Added
  • More useful debug, logs and dialog messages

### Fixed
  • Window not closed properly after the first relaunch

### Changed
  • Disallowed Java installs below Java 21 from being detected
  • Disallowed Java installs below Java 21 from working

### Added
  • Auto Java Detection
  • Java 9+ Process API usage to check if parent process is alive, much more reliable than older method
  • Certs fix for older Java 8 users
  • Relauncher now pops up if a newer Cleanroom version is fetched

### Changed
  • Configuration now moved to config/relauncher.json

### Fixed
  • Various GUI scaling, position issues

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