Running UnityHub from [Flatpak](https://flathub.org/apps/com.unity.UnityHub) is also still an option, but it seems ALCOM has better integration with the AppImage.
First, take a look at this page from [the official VRChat docs](https://creators.vrchat.com/sdk/upgrade/unity-2022/#using-the-unity-hub) about how to install the supported Unity version from UnityHub. We'll do something similar.
1. Install **2022.3.22** (VRChat's current supported Unity version, at the time of writing) by running `./UnityHub.AppImage unityhub://2022.3.22f1/887be4894c44`.
- You may need to install `cpio` from your distro's repos in order to install these components (The AppImage erroneously doesn't include it). To check if it's installed, run `which cpio` in a terminal.
vrc-get is a native FOSS package manager written in Rust. Its GUI counterpart was formerly known as vrc-get-gui, but has been rebranded as ALCOM (***Al***ternative Creator ***Com***panion).
1. Download the [AppImage from the latest "gui" release](https://github.com/vrc-get/vrc-get/releases). Pick the file named `alcom-<some version>-x86_64.AppImage`.
1. Run the AppImage.
1. In the settings tab, under Unity Hub Path, point it to your UnityHub.AppImage.
The official VRChat Creator Companion uses Webview2 (Microsoft Edge). This component is difficult to install, and doesn't run natively. Instead, you can use LinuxCreatorCompanion.
It works by using wine to extract the necessary bits to re-embed into a native client application. While experimental, you can enjoy much easier avatar, world, and asset creation. Again, this is experimental, and we discourage you from trying this on important projects. **Remember to make frequent project backups.** Please leave any feedback about bugs or ideas on the GitHub issues tab.
**Note:** If you're using Unity Hub via flatpak, it will have trouble finding and opening Unity. For now, create this wrapper script, chmod +x it, and put it somewhere in your PATH, like `/usr/local/bin/unityhub`.
This error is caused by VRCSDK build incorrectly expecting a mixed-case AssetBundle filename, while Unity outputs a lowercase filename, which fails a file existence check and causes the SDK to abort the build.
### Avatars: Local test avatars don't show up ingame
The "Build & Test" button on the SDK will create avatar AssetBundles (.vrca). However (and assuming the build succeeds), it writes them to a different location than VRChat's Proton prefix. Just symlink and try the build again.
This can happen with Poiyomi. It's caused by case-sensitivity. You may need to edit the shader files directly. Open them in any text editor, and correct the casing of filenames.
Rather than using Assets -> Import New Asset or Import Package, it's normally possible to drag-and-drop a unitypackage or other asset from a file browser directly into Unity's Project pane, where it will be copied to the Assets folder.
However, if your file browser is running on Wayland, this will show "Failed copying file" errors.
See issue [flathub/com.unity.UnityHub#97](https://github.com/flathub/com.unity.UnityHub/issues/97).
As a workaround, launch your file browser in Xwayland mode. Unity will accept the file as it should.
Analysis: ALCOM has a different environment than the rest of your system, mostly by virtue of being an AppImage. This means the Unity subprocess that it spawns was implicitly inheriting its crummy vars. Unfun fact: This environment inheritance causes several other problems (such as ignoring the user's GTK theme for menubars and context menus, especially on a KDE system), but I'm not sure the cleanest way to unset those vars yet. A wrapper script around the Unity binary?
Maybe due to the windows offscreen issue mentioned above, when starting build or play mode, the VRCFury progress window may initially be invisible, or pop underneath, which gives the *appearance* that the build isn't doing anything and has locked up. Use the "Alt-tab to the specific window then Meta-Right" trick to get the VRCFury progress window to appear onscreen again. That window may also be solid black, but this doesn't necessarily mean the build has frozen.
### Moving file failed
A dialog may appear upon trying to build an avatar, where none of the buttons are helpful:
> Moving Temp/unitystream.unity3d to /tmp/DefaultCompany/Some Avatar Project/prefab-id-v1\_avtr\_00000000-0000-0000-0000-000000000000_0000000000.prefab.unity3d:
This seems to happen consistently if the projects are stored on an EXFAT partition. Consider using another filesystem, such as NTFS if you still need projects accessible under both Windows and Linux.
If you launch projects from ALCOM (v0.1.13 or newer): Open ALCOM, go to the "Default Unity Command-line Arguments" setting on the Settings page. Click "Edit", "Customize", "Reset", "+", then type in `-force-vulkan-layers` into the new box, then click "Save".
If you launch projects from Unity Hub: Open Unity Hub, click the `...` icon to the right of your project, then click "Add command line arguments", and add the argument `-force-vulkan-layers`.
<!-- This fix is mentioned in https://discussions.unity.com/t/unity-editor-crashes-frequently-on-linux-vulkan-after-updating-gpu-drivers/941387/10, and appears to be a new issue as of driver version 550 -->