Yes, you can run mods on an Astroneer dedicated server, but the process is more involved than copying a few files. Build the mod set on a Windows PC, generate the required 999-AstroModIntegrator_P.pak, and place that file plus the server-required mod Paks in the server’s Astro/Saved/Paks folder. Mods marked sync="serverclient" must also be installed by every player at matching versions; sync="server" mods stay on the server, while sync="client" mods stay on individual PCs.
Community tools make dedicated-server modding possible, but System Era Softworks does not officially support mods. Back up the server and saves before changing anything, and check compatibility carefully: the Megatech update moved Astroneer from Unreal Engine 4.23 to 4.27, making older mods unusable.
Can you use mods on an Astroneer dedicated server?
Yes. The AstroTechies Astroneer Modding FAQ states, “Yes, you can use mods on dedicated servers.” That is a community-tooling capability rather than an official support promise from the game developer.
System Era Softworks’ December 9, 2025 Megatech troubleshooting notice warns: “We do not officially support mods, so if you have used them on any of your old saves, you are likely going to crash.” Treat a modded server as an unsupported configuration. Keep a clean backup, test changes on a copy when possible, and be prepared to remove the mod Paks if the server or save becomes unstable.
What do I need before installing Astroneer server mods?
A dedicated-server installation
Install Astroneer Dedicated Server from Steam by opening Library > Tools. Launch it once so the required folders and configuration files are created, then stop it before editing anything.
A Windows PC for the standard toolchain
The commonly documented workflow uses AstroModLoader Classic on Windows. Mods are distributed as Unreal Engine .pak files, and the mod integrator is required to combine the enabled set into a server-readable package.
A backup made while the server is stopped
Stop the server and copy the save data and configuration somewhere separate before replacing or adding Paks. A portable external SSD can be useful for this backup, but it is optional hardware, not a modding requirement. If a world depends on mod content, retain the pre-change save so you can restore it if you return to vanilla.
A compatibility check for every mod
The Megatech update changed Astroneer’s Unreal Engine version from 4.23 to 4.27. AstroTechies reports that mods last updated before November 21, 2025 are incompatible with the latest version and that mods built for game version 1.35 or earlier are guaranteed not to function with the current game build, documented as 1.36.42.0.
Before uploading a Pak, inspect its metadata and documentation. Confirm the mod’s game_build value and last-updated date. Do not assume that a Pak that worked before Megatech will load after the engine migration.
How does Astroneer mod synchronization work?
Each mod’s sync metadata determines where it belongs. The default category is serverclient; if a mod has no sync value, treat it as serverclient unless the mod’s own documentation explicitly says otherwise.
| Sync value | Install on the server? | Install on players’ PCs? | Use |
|---|---|---|---|
serverclient |
Yes | Yes, for every player, at a matching version | Content or behavior that must exist on both sides |
server |
Yes | No | Server-side functionality that does not require a client Pak |
client |
No | Only on each interested player’s PC | Client-only changes; keep these out of the server set |
No sync value |
Treat as serverclient | Treat as serverclient | Use the author’s documentation if it specifies a different category |
Make a written list of the serverclient Paks and their versions. Give that exact list to every player who joins. A client with a missing or different serverclient Pak can be unable to join, lose modded features, or encounter instability.
How do I install mods on a self-hosted Astroneer server?
1. Create and initialize the dedicated server
- In Steam, open Library > Tools.
- Install Astroneer Dedicated Server.
- Launch the server once, wait for its folders to be generated, and stop it cleanly.
Do not edit files while the process is running. System Era’s server guidance states that changes made while the server is active will not be saved.
2. Locate the configuration directory
Inside the dedicated-server installation, open Astro/Saved/Config/WindowsServer. The official configuration files are Engine.ini and AstroServerSettings.ini. Edit them only after stopping the server, save the files, and close your editor before restarting.
3. Install a compatible mod manager
On a Windows PC, install a supported manager such as AstroModLoader Classic. Obtain each mod from its current distribution and keep the original Pak filename intact. Do not rename files to generic names such as mod1.pak; intact names make it easier to compare the server and client sets and to identify an incompatible file.
4. Sort the mods by sync category
Read each mod’s metadata or documentation and classify it as serverclient, server, or client. Put serverclient and server mods in the set that will be integrated for the dedicated server. Do not upload client-only Paks to the server. Prepare a separate client package containing every serverclient mod so that all players can install matching versions.
If a mod does not declare sync, handle it as serverclient unless its documentation says otherwise. This conservative choice prevents a player from joining with an incomplete dependency set.
5. Run the integrator
Run AstroModLoader Classic with the complete enabled set. It creates 999-AstroModIntegrator_P.pak. That Pak is required; uploading the individual mod files without the generated integrator can leave the server appearing completely vanilla.
Re-run integration after every Astroneer game update and whenever you add, remove, disable, or replace a mod. The integrator must represent the current set, not the list you used for an earlier build.
6. Move the generated files to the server machine
You have two documented options:
- Run AstroModLoader Classic from the server installation. Its FAQ documents an optional
--serverargument for this arrangement. - On the PC where the loader ran, copy the local
%localappdata%/Astro/Saved/Paksfolder, including the freshly generated integrator Pak, to the server machine.
Copy only the Paks required by the server: all serverclient and server files plus 999-AstroModIntegrator_P.pak. Keep client-only files in the players’ local mod folders.
7. Upload the Paks and restart
Stop the dedicated server, make or refresh your backup, and place the files in Astro/Saved/Paks. In a hosted control panel, use its file manager or SFTP destination that maps to this same path. Preserve every filename and extension, then start the server and test a feature supplied by one of the installed mods.
Where exactly do Astroneer .pak files go on a server?
The destination is the server’s Astro/Saved/Paks directory. A typical final layout includes the generated integrator and the individual server-required Paks:
Astro/Saved/Paks/999-AstroModIntegrator_P.pak
Astro/Saved/Paks/ExampleServerMod.pak
Astro/Saved/Paks/ExampleSharedMod.pakThe names above illustrate the layout only; use the real filenames supplied by each mod. Do not place the files in Astro/Saved/Config/WindowsServer, the game’s top-level installation directory, or a client-only mod folder. Configuration files belong in the Config directory, while Pak content belongs in Paks.
After uploading, check that the integrated Pak is present and that its timestamp reflects the latest integration run. If your panel presents separate home, save, and installation roots, navigate until the path ends exactly in Astro/Saved/Paks for the dedicated-server instance you are starting.
How do I install mods on a Linux or Proton host?
A Linux host needs a loader path that matches its runtime. AstroTechies documents four approaches: the native Linux astro_modloader, AstroModLoader Classic through Wine, UE4SS plus AutoIntegrator through Proton, and the native Linux ModIntegrator binary.
A Windows-only loader cannot simply be assumed to run natively on Linux. Choose one of the documented combinations, generate the same 999-AstroModIntegrator_P.pak, and then copy the resulting server Paks into the Linux server’s equivalent Astro/Saved/Paks path. Confirm that the loader and the dedicated-server process are using the same game installation and save location; otherwise you may integrate files that the running server never reads.
Why is my Astroneer modded server starting vanilla?
A vanilla start usually means the server is not reading the expected Pak set or the integration file is missing or stale.
- Confirm that the files are under
Astro/Saved/Paksfor the active server instance. - Check that every Pak filename and extension is intact.
- Verify that
999-AstroModIntegrator_P.pakexists. - Run the integrator again after enabling the current mod list, then replace the old integrator on the server.
- Restart the server only after the upload is complete.
Test a clearly visible modded feature rather than relying on the presence of files alone. A file copied to a different installation or an integrator generated from an empty list can leave the server apparently healthy but unmodified.
What should I do if the server crashes after an Astroneer update?
Stop the server and treat the update as a compatibility event. Rebuild the integration, then inspect every mod’s game_build metadata and last-updated date. Mods built for 1.35 or earlier are guaranteed not to function with the current 1.36.42.0-era build, and AstroTechies identifies November 21, 2025 as the cutoff for mods updated before the latest version.
- Stop the server and preserve the crash-affected installation.
- Restore the pre-update backup if you need the world available immediately.
- Remove or quarantine Paks that fail the compatibility check.
- Re-integrate only mods confirmed for the current game build.
- Restart and test before adding the remaining mods one at a time.
If the crash persists, remove the mod Paks and use the clean backup. System Era’s warning about unsupported mods is especially relevant to old saves that have previously contained mod content.
Why can’t players join, or why are mod features missing?
Compare the server’s serverclient list with every player’s installed list. The files must match in both membership and version; a player who lacks one shared Pak can fail to join, while a mismatched version can produce missing features or instability.
Server starts but one player is rejected
Have that player close the game, update or remove the mismatched serverclient Paks, and install the exact versions used by the server. Client-only mods are not a substitute for missing serverclient files and should not be uploaded to the server.
Everyone joins but shared content is absent
Check that the mod is actually classified as serverclient, that its Pak is on the server, and that a fresh integrator was generated after it was enabled. If its documentation lists another sync category, follow that category instead of guessing from the filename.
How do I return a modded server to vanilla?
Stop the server before changing its files. Move the mod Paks and 999-AstroModIntegrator_P.pak out of Astro/Saved/Paks, or restore the clean server backup. If the world was created or saved with mod-dependent content, restore the corresponding clean save rather than assuming that removing files alone will repair it.
Keep the removed Paks in a separate archive while testing. That preserves the exact mod set and versions in case you need to reproduce the world later, while the running installation remains free of mod files.
Which installation approach should I use?
The right method depends on your operating system, file access, and tolerance for maintaining the integration yourself.
| Approach | Host-runtime requirement | Client installation | Update and integration work | Files and backup considerations |
|---|---|---|---|---|
| Windows self-host with AstroModLoader Classic | Windows loader and dedicated-server installation | Required for serverclient mods | Re-run integration after game or mod-list changes | Direct access to local files; create your own server and save backups |
| Linux native loader | Native Linux astro_modloader or native ModIntegrator |
Required for serverclient mods | Use the Linux-compatible integration path after each change | Verify the loader writes to the same installation used by the server |
| Linux with Wine or Proton | AstroModLoader Classic through Wine, or UE4SS plus AutoIntegrator through Proton | Required for serverclient mods | Rebuild with the selected compatibility layer after updates | Check path mapping and retain a rollback backup |
| Hosted control panel | Provider must permit the required loader workflow or Pak uploads | Required for serverclient mods | Use local integration, then upload through file manager or SFTP | Confirm access to Astro/Saved/Paks and whether managed backups are included |
Before choosing a host, verify that you can access the server files or SFTP, upload Paks, create and download backups, and run the loader somewhere compatible with the provider’s operating system. Cross-play availability and managed-backup policies vary by provider, so confirm them directly rather than assuming a mod-capable server includes either service.
What is the safest update routine for a modded server?
- Announce a maintenance stop and shut down the server cleanly.
- Back up the save, configuration, and current Pak set.
- Check the new Astroneer build number and each mod’s
game_buildand update date. - Remove mods that fail the compatibility gate.
- Regenerate
999-AstroModIntegrator_P.pakwith the remaining, compatible set. - Upload the individual server Paks and the new integrator to
Astro/Saved/Paks. - Start the server, test a modded feature, and have a player verify the matching serverclient set before reopening the server.
Keep a simple manifest containing each Pak filename, version, sync category, and source date. That record makes it possible to identify the first change when a later update causes a crash or a join failure.
Frequently Asked Questions
Can a hosted Astroneer server use mods if I do not have desktop access to the machine?
Yes, provided the service gives you a compatible way to generate the integration and upload files through a panel or SFTP. Confirm that you can reach the instance’s Astro/Saved/Paks directory and make downloadable backups before committing to the setup.
Should I upload cosmetic or interface-only mods to the dedicated server?
Only if the mod is marked serverclient or server. A client mod belongs on each interested player’s PC and should remain outside the server’s Pak set.
What happens to a world that used a mod after I remove the mod files?
The save may still depend on mod-created content even after the Paks are removed. Keep the original save and restore a clean backup when returning to vanilla instead of assuming that file removal repairs the world.
How can I tell whether an old Pak is safe after Megatech?
Check its declared game_build and last-updated date against the current Astroneer build. Mods built for 1.35 or earlier are not compatible with the current 1.36.42.0-era version, and mods updated before November 21, 2025 should be treated as incompatible according to AstroTechies.