error when attempting to download and use any version, either via local save zip or the portal: "the mod-file for mod metal-and-stars doesn't exist!"

Not sure what the cause is, but all other mods download and function fine :( I uninstalled to downgrade version and now I can't start my server! :(

looking into this now. Gemini offered this feedback. If you can give me any more details, that would be helpful.
consider asking Gemini (or chatGPT) for more help while I try to solve this.

This error message, "the mod-file for mod metal-and-stars doesn't exist!", indicates that Factorio cannot find the actual mod file (usually a .zip file) for the "metal-and-stars" mod. Here's a troubleshooting guide to help you resolve this:

1. Verify Mod Installation Location:

   Factorio Mods Folder: Factorio looks for mods in a specific folder. The location varies slightly by operating system:
   Windows: %appdata%\Factorio\mods (you can type this directly into the Windows search bar or File Explorer address bar)
   macOS: ~/Library/Application Support/Factorio/mods
   Linux: ~/.factorio/mods
   Check for metal-and-stars_X.Y.Z.zip: Inside this mods folder, you should see a .zip file for the "metal-and-stars" mod. The X.Y.Z will be the version number (e.g., metal-and-stars_1.2.3.zip).
   Common Mistakes:
   Unzipped Folder: Sometimes users accidentally unzip the mod directly into the mods folder, creating a subfolder like mods/metal-and-stars/ instead of mods/metal-and-stars_X.Y.Z.zip. Factorio needs the .zip file.
   Incorrect Subfolder: Make sure the .zip file isn't nested within another unnecessary folder.

2. Redownload the Mod:

   Corrupted Download: The original download might have been corrupted or incomplete.
   Source: Go back to where you originally downloaded the "metal-and-stars" mod (Factorio Mod Portal, GitHub, etc.) and download it again.
   Replace Existing: Delete the old (potentially problematic) metal-and-stars mod file from your mods folder before placing the newly downloaded one there.

3. Check Mod File Name and Version:

   Exact Match: Factorio is very particular about mod filenames. The filename must follow the modname_version.zip convention (e.g., metal-and-stars_1.0.0.zip).
   Typos: Double-check for any typos in the filename.
   Missing Version: Ensure the version number is included in the filename.
   Double Extension: Sometimes Windows hides file extensions, leading to issues like metal-and-stars_1.0.0.zip.zip. Make sure "Hide extensions for known file types" is unchecked in your File Explorer options to see the full filename.

4. Check Factorio's Mod List (In-Game):

   Launch Factorio: Start the game.
   Mods Menu: Go to "Mods" from the main menu.
   Verify Presence: Even if it's giving an error, the "metal-and-stars" mod should still appear in the list.
   Enabled/Disabled: Make sure it's enabled. If it's disabled, enable it and restart Factorio.
   Dependency Issues: Sometimes this error can be a symptom of a missing dependency. Check the mod's description on its download page to see if it requires any other mods to be installed.

5. Check Factorio Log File:

   Location: The Factorio log file (factorio-current.log) can provide more detailed information about what's going wrong.
   Windows: %appdata%\Factorio\factorio-current.log
   macOS: ~/Library/Application Support/Factorio/factorio-current.log
   Linux: ~/.factorio/factorio-current.log
   Search for Errors: Open this file with a text editor (like Notepad, VS Code, or Sublime Text) and search for "metal-and-stars" or "error" around the time you tried to load the mod. It might give a more specific reason for the failure.

6. Permissions Issues:

   File Access: In rare cases, Factorio might not have the necessary permissions to read the mod file.
   Try Running as Administrator (Windows): Right-click on the Factorio shortcut and select "Run as administrator." This can sometimes resolve permission problems. (Be cautious with this for general use, but it's a good troubleshooting step.)

7. Game Version Compatibility:

   Mod Version vs. Game Version: Ensure the "metal-and-stars" mod you're trying to use is compatible with your current version of Factorio. Mods designed for older or newer versions of Factorio might not work correctly and could lead to this error. Check the mod's download page for compatibility information.

From Docker Container log for Factorio Server Manager:

2025/06/25 21:17:38 the mod-file for mod metal-and-stars doesn't exist! 2025/06/25 21:17:38 error when deleting mod: the mod-file for mod metal-and-stars doesn't exist! 2025/06/25 21:17:38 error when creating Mod: the mod-file for mod metal-and-stars doesn't exist! 2025/06/25 21:17:38 Error downloading a mod: the mod-file for mod metal-and-stars doesn't exist!

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I tried manually downloading the zip and I get the same error when I go to upload the file, it's quite odd.

Again, other mods update, downgrade, uninstall/re-install properly, this is the only headache at the moment. Thanks in advance!

This looks like a Factorio Server Manager bug, see here for a similar one
https://github.com/OpenFactorioServerManager/factorio-server-manager/issues/329

Thank you very much for the response, I hope they can fix that.

For now, due to the errors caused by the accidental removal of Metal and Stars, I have written a Hotfix mod that will successfully allow players to remove M&S from a playthrough without encountering server errors due to missing item subgroups.

https://mods.factorio.com/mod/ringworld-subgroup-fix

Thanks for all your help!