# mc-multilogin-compat-mod<\/p>\n
A Fabric server-side mod for Minecraft **1.21.1** (Mojang mappings) that integrates with
\nMC-MultiLogin-service.<\/p>\n
\u4e00\u4e2a\u7528\u4e8e Minecraft 1.21.1\uff08Mojang \u6620\u5c04\u8868\uff09\u7684 Fabric \u670d\u52a1\u7aef\u6a21\u7ec4\uff0c\u7528\u4e8e\u4e0e MC-MultiLogin-service \u96c6\u6210\uff0c\u53ef\u4ee5\u5b9e\u73b0\u591a\u6e90\u767b\u5f55\u65b9\u5f0f\u3002<\/p>\n
We suggest you to use this with Authlib-Injector. This mod only change the login method and the login-failed message.<\/p>\n
\u5efa\u8bae\u914d\u5408 Authlib-Injector \u4f7f\u7528\u3002\u6b64\u6a21\u7ec4\u4ec5\u4fee\u6539\u767b\u5f55\u65b9\u5f0f\u548c\u767b\u5f55\u5931\u8d25\u65f6\u7684\u63d0\u793a\u4fe1\u606f\u3002\u5982\u679c\u60a8\u4f7f\u7528`Authlib-Injector`\uff0c\u8bf7\u8bb0\u5f97\u8bbe\u5b9a\u5b83\u7684\u94fe\u63a5\u4e3a `MC-MultiLogin-service`\u63d0\u4f9b\u7684API\u5730\u5740\u3002<\/p>\n
## Velocity Plugin Version
\nConfig can be found at `pluginsmultilogin-auth-compatmultilogin-compat-config.json`.<\/p>\n
\u914d\u7f6e\u53ef\u4ee5\u5728`pluginsmultilogin-auth-compatmultilogin-compat-config.json`\u627e\u5230\u3002<\/p>\n
## Fabric Mod Version
\n### Features<\/p>\n
– On every player login the mod calls the configured MC-MultiLogin-service endpoint with
\n `detail=true`, so authentication failures return a structured JSON error instead of the
\n generic “Failed to verify username!” message.
\n– Detailed error reasons (`DUPLICATE_NAME`, `BANNED`, `NOT_FOUND`, \u2026) are forwarded directly
\n to the connecting client in the disconnect screen.
\n– **Auto-rename on `DUPLICATE_NAME`** (configurable): when the service reports that a player
\n name is already taken by another skin-site account, the mod automatically retries the login
\n with the service-suggested `availableId` (e.g. `Steve_2`) and records the
\n original \u2192 new-name mapping in `config\/mc-multilogin-renames.json`.<\/p>\n
### Setup<\/p>\n
1. Place the mod JAR in your server’s `mods\/` directory.
\n2. Start the server once \u2013 a default config file will be generated at
\n `config\/mc-multilogin-compat.json` and the server will **stop with an error** asking you
\n to fill in the API URL.
\n3. Edit the config and set `apiUrl` to the base URL of your MC-MultiLogin-service method
\n entry (e.g. `http:\/\/127.0.0.1:25600\/login\/my`).
\n4. Restart the server.<\/p>\n
## Configuration (`config\/mc-multilogin-compat.json`)<\/p>\n
“`json
\n{
\n “apiUrl”: “http:\/\/127.0.0.1:25600\/login\/my”,
\n “autoRename”: true
\n}
\n“`<\/p>\n
| Field | Type | Default | Description |
\n|————-|———|———|————-|
\n| `apiUrl` | string | `””` | **Required.** Base URL of the MC-MultiLogin-service login method (e.g. the path configured under `method[].url`). The mod appends `\/session\/minecraft\/hasJoined?\u2026` automatically. |
\n| `autoRename`| boolean | `true` | (Not working at present) When `true`, a `DUPLICATE_NAME` rejection triggers an automatic retry using the `availableId` returned by the service. The rename is persisted in `config\/mc-multilogin-renames.json`. Set to `false` to disable and show the error instead. |<\/p>\n
### Building<\/p>\n
“`bash
\n# Requires Java 21 and internet access to maven.fabricmc.net
\n.\/gradlew build
\n“`<\/p>\n
The output JAR will be in `build\/libs\/`.<\/p>\n","protected":false},"excerpt":{"rendered":"
A Fabric server-side mod for Minecraft 1.21.1(maybe other versions) that integrates with project MC-MultiLogin-service.<\/p>\n","protected":false},"featured_media":0,"template":"","meta":{"_minecraft_slug":"multilogin-compat-mod","_minecraft_project_id":"4Yyw6Tvg","_minecraft_author":"wifi-left","_minecraft_license":"LicenseRef-All-Rights-Reserved","_minecraft_downloads":84,"_minecraft_follows":1,"_minecraft_client_side":"unsupported","_minecraft_server_side":"required","_minecraft_storage_type":"zip","_minecraft_archive_name":"multilogin-compat-mod.zip","_minecraft_size_bytes":51373,"_minecraft_version_count":3,"_minecraft_updated_at":"2026-05-15T20:05:06.648113Z","_minecraft_date_created":"2026-03-31T04:27:40.515528Z","_minecraft_date_modified":"2026-04-01T14:53:14.080824Z","_minecraft_project_url":"https:\/\/modrinth.com\/mod\/multilogin-compat-mod","_minecraft_icon_attachment_id":0,"_minecraft_imported_at":"2026-06-06T05:07:05+00:00","_minecraft_import_hash":"7c2fa6f6d691ccfce4c7d87afb6625f5","_minecraft_versions":"","_minecraft_links":"","_minecraft_gallery":"","_minecraft_api_metadata":""},"mod_category":[97,126,92,985],"mod_loader":[99],"minecraft_version":[118,119,120,46,47,48,49,50,51,52,53,54,55,56,57,58,59,36,60,93,94,101,102,62,37,40,41,73,74,38,78,79,80,81,82,83,167],"class_list":["post-107508","mod","type-mod","status-publish","hentry","mod_category-fabric","mod_category-management","mod_category-utility","mod_category-velocity","mod_loader-fabric","minecraft_version-1-16","minecraft_version-1-16-1","minecraft_version-1-16-2","minecraft_version-1-16-3","minecraft_version-1-16-4","minecraft_version-1-16-5","minecraft_version-1-17","minecraft_version-1-17-1","minecraft_version-1-18","minecraft_version-1-18-1","minecraft_version-1-18-2","minecraft_version-1-19","minecraft_version-1-19-1","minecraft_version-1-19-2","minecraft_version-1-19-3","minecraft_version-1-19-4","minecraft_version-1-20","minecraft_version-1-20-1","minecraft_version-1-20-2","minecraft_version-1-20-3","minecraft_version-1-20-4","minecraft_version-1-20-5","minecraft_version-1-20-6","minecraft_version-1-21","minecraft_version-1-21-1","minecraft_version-1-21-10","minecraft_version-1-21-11","minecraft_version-1-21-2","minecraft_version-1-21-3","minecraft_version-1-21-4","minecraft_version-1-21-5","minecraft_version-1-21-6","minecraft_version-1-21-7","minecraft_version-1-21-8","minecraft_version-1-21-9","minecraft_version-26-1","minecraft_version-26-1-1"],"yoast_head":"\n