Install apps on muOS: .muxapp and .muxzip files with Archive Manager

Apps for muOS come as a single file ending in .muxapp. You don’t unzip it or copy folders around: muOS has a built-in installer called Archive Manager that does it for you. This guide shows the whole process, what happens behind the scenes, and the two things that catch people out: updates that reset your settings, and how to uninstall.

Tested on: Anbernic RG40XXH · muOS 2601.0 Jacaranda. Other muOS handhelds work the same way.

What a .muxapp file is

A .muxapp file is an ordinary ZIP archive with a different ending. Inside is one folder named after the app, for example:

WiFiTransfer.muxapp
└── WiFiTransfer/
    ├── mux_launch.sh    ← muOS starts the app with this
    ├── config.ini
    └── …

Installing it means unpacking that folder into MUOS/application/ on your SD card. Every app in that folder shows up in the Applications menu.

Step 1: Copy the file to the ARCHIVE folder

Archive Manager lists the files in the ARCHIVE folder at the top of SD card 1 (the card muOS runs from). If the folder isn’t there, create it, in capitals.

There are three easy ways to get the file there:

Card reader: turn the handheld off, put SD card 1 in your computer and copy the .muxapp file into ARCHIVE. Eject the card properly before taking it out.
Over Wi-Fi with Wi-Fi Transfer: open the app on the handheld, open the address it shows in your phone or PC browser, and on the SD card 1 tab tap Add games and pick the .muxapp. It goes into ARCHIVE automatically.
SFTP: muOS can run an SFTP server: turn on SFTP + Filebrowser in Configuration → Connectivity → Web Services. Any SFTP app (FileZilla, Cyberduck, WinSCP) can then copy the file into ARCHIVE on SD card 1.

Keep the file name as it is: Archive Manager decides what to do from the ending (.muxapp).

Step 2: Install it with Archive Manager

On the handheld, open Applications → Archive Manager.
Select the .muxapp file and press A.
muOS closes its menus and shows a text screen while it works: Inspecting Archive…, the files being extracted, Sync Filesystem and finally All Done!
After a couple of seconds you’re back in Archive Manager. The file is now marked INSTALLED.

Open Applications: the new app is in the list. Some apps also need Wi-Fi turned on (Configuration → Connectivity → Wi-Fi Network) before you start them.

The .muxapp file stays in ARCHIVE after installing. You can keep it as a backup or delete it; the installed app doesn’t need it.

What Archive Manager actually does

Before it extracts anything, Archive Manager checks the archive and refuses it if any path inside points outside its target folder (an absolute path or ..). So a broken or malicious package can’t overwrite muOS system files that way.

That check is about file locations, not about what the app does once it runs. Apps on muOS run with full access to the system, so only install .muxapp files from sources you trust: the developer’s own website or GitHub releases page.

Archive Manager isn’t only for apps. It picks the install method from the file ending:

Ending	What it is	Where it goes
`.muxapp`	Application	`MUOS/application/`
`.muxthm`	Theme	`MUOS/theme/<name>/`
`.muxalt`	Alternative look for the current theme	the active theme’s folder
`.muxzip`	Content package (for example saves, BIOS or collections, depending on what’s inside)	the matching muOS folders
`.muxcat`	Catalogue package (box art and descriptions)	`MUOS/package/catalogue/`
`.muxcfg`	RetroArch configuration package	`MUOS/package/config/`
`.muxupd`	muOS system update	the system itself

Updating an app: save your settings first

To update, copy the newer .muxapp into ARCHIVE and install it the same way. Archive Manager unpacks it over the existing app folder:

files that are in the new package replace the old ones, including config.ini;
files that aren’t in the package, like an app’s data/ or logs/ folder, are kept.

So anything you changed in the app’s config.ini goes back to the default after an update. Before updating, copy the app’s config.ini somewhere safe (or write down your settings), then put your changes back afterwards. Game Manager is an exception: its package has no config.ini, so an update keeps your settings, including your itch.io API key. Your installed-games list is in data/ and survives the update.

If the newer file has the same name as the old one, delete or replace the old file in ARCHIVE first, so you’re sure which one you’re installing.

Uninstalling an app

muOS 2601 has no uninstall button for apps. To remove one, delete its folder:

SD card 1 → MUOS/application/<AppName>

Do it with a card reader, over SFTP, or with Wi-Fi Transfer. Then go back to the main menu and open Applications again; the app is gone. Deleting the folder also deletes the app’s own settings and data, so copy anything you want to keep first.

Troubleshooting

Archive Manager says “No Archives Found”: the file isn’t in ARCHIVE at the top of SD card 1, or the folder name is wrong. It has to be ARCHIVE, not inside ROMS or MUOS.
The file is listed but installing fails with “unsafe paths”: the package was built wrongly. Contact the app’s developer; don’t try to unpack it by hand.
“Could not open archive… Corrupt?”: the download didn’t finish or the copy was cut short. Download it again and, if the developer gives a SHA-256 checksum, compare it (shasum -a 256 file.muxapp on a Mac or Linux).
The app installed but doesn’t appear: go back to the main menu and open Applications again. If it’s still missing, check that MUOS/application/<AppName>/mux_launch.sh exists.
The app starts and closes straight away: many apps write a log in their own folder, usually logs/app.log. Check it, and turn on Wi-Fi if the app needs the internet.

Summary

Put the .muxapp file in ARCHIVE on SD card 1.
Applications → Archive Manager, select it, press A, wait for All Done!
Open the app from Applications.
Before updating, save the app’s config.ini. To uninstall, delete its folder in MUOS/application/.

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