This page covers the most common problems you may run into while using Ferrumium, organized by area. Each entry describes what you see, why it happens, and how to fix it.

Login and authentication

You see a 401 error or get redirected to the login page

Your session has expired, been revoked, or your account has been banned. Ferrumium automatically redirects you to the login page when your session is no longer valid.

To fix this, log in again. If you revoked your own sessions from Settings > Security, that is the cause. If your account was banned, the ban will lift automatically when it expires.

OAuth login fails with Discord, Steam, or Patreon

The OAuth provider did not return the expected token or profile data. This usually means you denied a permission prompt, the provider had a temporary outage, or your browser blocked the redirect.

Try again. Make sure you approve all requested permissions. If the problem persists, try a different browser or clear your cookies for the Ferrumium domain.

Password reset link does not work

Password reset tokens expire after 30 minutes. If you clicked the link after that window, it will fail.

Request a new password reset from the login page.

Uploads

Save file rejected

Ferrumium accepts .sav files only, with a maximum size of 100 MB. Save files from before Satisfactory Update 8 are not supported and will be rejected with a message explaining why.

If your file is valid and under the size limit, make sure it is not corrupted. Re-export it from the game and try again.

Blueprint upload rejected

Blueprints require a .sbp file. A .sbpcfg file is optional but, if included, its filename must match the .sbp file. The combined size limit is 50 MB.

Check that both filenames match exactly (excluding the extension) and that the total size is within the limit.

Gallery image upload rejected

Gallery images must be .webp, .png, .jpeg, .jpg, or .gif format, with a maximum size of 10 MB.

Resize or convert your image if it exceeds these limits.

413 error on upload

A 413 response means your file exceeds the server's size limit. Check the limits listed above for your file type and reduce the file size.

422 error on upload

A 422 response means the server could not parse your file. The file may be corrupted, or it may be from a legacy game version that Ferrumium does not support.

Re-export the file from the game. If you are uploading a save from before Update 8, it is not supported.

Co-op sessions

You cannot join a co-op session

Invite links can expire or be revoked by the factory owner. Each factory plan supports a maximum of 8 participants. If the room is full, you will see an error when trying to join.

Ask the owner for a new invite link, or wait for a slot to open.

You joined but cannot edit

Co-op sessions have three roles: owner, editor, and viewer. Viewers can watch but cannot make changes. Only the factory owner can change participant roles.

Ask the owner to promote you to editor.

Co-op connection error codes

When a co-op connection closes unexpectedly, the error code tells you what happened:

• 4000: your old connection was replaced because you reconnected from another tab or device. Your cursor color is preserved.
• 4001: authentication failure. Log in again.
• 4003: you do not have access to this factory plan.
• 4429: the room is full (maximum 8 participants).

Connection and network

Connection issues during co-op

Ferrumium uses a live connection for real-time features like co-op. The connection goes through several states: connecting, connected, and reconnecting. When disconnected, the status indicator is hidden — if you notice co-op features are unresponsive, check your internet connection.

If you are stuck in "reconnecting," check your internet connection, firewall settings, and any browser extensions that might block live connections. Corporate firewalls and VPNs sometimes interfere.

Network errors on page load or API calls

These usually mean you are offline or a firewall is blocking requests.

Check your internet connection. If you are on a restricted network, try a different network or disable your VPN temporarily.

Planner

Connection warnings on nodes

The planner shows inline warnings when your factory layout has issues:

• Belt Bottleneck: a belt cannot carry the required throughput.
• Input Starvation: a machine is not receiving enough input.
• Oversupply Warning: a machine is producing more than downstream machines can consume.

See the FAQ page under Reference for detailed explanations of each warning and how to resolve them.

Undo and redo are not available

Undo and redo are disabled during co-op sessions to prevent conflicts between participants.

Rate calculations feel slow or laggy

In performance mode, the planner waits slightly longer before recalculating production rates. This reduces load but can make updates feel delayed.

If the lag is disruptive, check your performance profile in Settings > Factory Planner > Performance. See the Performance Tips page for details.

Rate limits

429 error

A 429 response means you have exceeded the per-user rate limit. This limit exists to prevent abuse.

Wait a moment and retry your request. If you are hitting this limit during normal use, reduce the frequency of your actions (for example, avoid rapid repeated saves).