Prusa error 13401 (Connect Registration Failed) appears on the MK4 and its equivalents are #26401 on the MK4S, #27401 on the MK3.9S, #21401 on the MK3.9, #28401 on the MK3.5S, #23401 on the MK3.5, and #31401 on the CORE One. The printer attempted to register with the Prusa Connect cloud service but the registration handshake failed.

What the Error Means

Prusa Connect registration involves the printer generating a one-time token, which you then enter in the Prusa Connect web interface (connect.prusa3d.com) to claim the printer to your account. The process requires an active Wi-Fi connection, correct network time for token validation, and that the token be entered before it expires. Registration fails when any of these conditions are not met — a weak or misconfigured Wi-Fi connection is the most common cause, followed by an expired token (tokens time out after approximately five minutes), and a printer that was previously registered to a different Prusa account without being properly removed.

Step-by-Step Fix

1. Check the Wi-Fi connection on the printer. Navigate to LCD Menu → Settings → Network and confirm the printer shows a valid IP address. If no IP is shown, troubleshoot the Wi-Fi connection first.
2. Restart the registration process from the printer. Go to LCD Menu → Settings → Prusa Connect and select Add printer or re-initiate registration. A fresh registration generates a new token.
3. Match the token exactly. The token displayed on the printer’s LCD must be entered character-for-character in the connect.prusa3d.com web interface. Tokens are case-sensitive.
4. Act quickly — tokens expire within minutes. Once a token is displayed, enter it in the web interface promptly. If you wait too long, start the registration process again to generate a new token.
5. Remove a conflicting registration if needed. If the printer was previously added to a different Prusa account, log into that account at connect.prusa3d.com and remove the printer entry before re-registering under the new account.
6. Check for DNS or firewall issues on your network. The printer must reach connect.prusa3d.com over port 443. If you use a network firewall, confirm outbound HTTPS traffic is not blocked.

Parts Required

• No replacement parts are required for this fix — this is a software/network issue only

If registration fails repeatedly despite a working network connection, contact Prusa Support at help.prusa3d.com with details about your network configuration.

Frequently asked questions

What does Prusa 13401 mean?

Prusa error 13401 (Connect Registration Failed) appears on the MK4 and its equivalents are #26401 on the MK4S, #27401 on the MK3.9S, #21401 on the MK3.9, #28401 on the MK3.5S, #23401 on the MK3.5, and #31401 on the CORE One. The printer attempted to register with the Prusa Connect cloud service but the registration handshake failed.

How do I fix Prusa 13401?

Prusa error 13401 means registration with Prusa Connect failed. Learn how to verify your network, token, and account to successfully register your printer to Prusa Connect.