Articles on: Troubleshooting

Why is my OctoPrint-powered printer offline?

Why is my OctoPrint-powered printer offline?


This guide helps troubleshoot why your OctoPrint-connected printer shows offline in SimplyPrint.


OctoPrint typically runs on a Raspberry Pi connected to your printer via USB. SimplyPrint connects through the SimplyPrint plugin installed in OctoPrint.



Start here: Where is the problem?


Step 1: Can you access OctoPrint?


Open OctoPrint in your browser (usually http://<pi-ip-address>).



Step 2: Is your printer connected in OctoPrint?


Look at OctoPrint's connection panel.



Note: SimplyPrint shows the same connection status as OctoPrint. If disconnected in OctoPrint, it will be offline in SimplyPrint.



Quick reference


Symptom

Likely cause

Solution

Offline in both SimplyPrint AND OctoPrint

USB/physical issue

Check USB cable

Offline in SimplyPrint only

Plugin issue

Check SimplyPrint plugin

"No serial port found"

Bad or wrong USB cable

USB cable troubleshooting

Keeps disconnecting randomly

Pi power issue

Check power supply

Prusa printer won't connect

"RPi port" setting enabled

Disable RPi port



2. SimplyPrint plugin issues


If your printer is connected in OctoPrint but offline in SimplyPrint, check the plugin.


Is the plugin enabled?


  1. In OctoPrint: Settings (wrench icon) > Plugin Manager
  2. Find "SimplyPrint Cloud"
  3. Make sure it's enabled (not grayed out)


Is OctoPrint in Safe Mode?


Safe Mode disables all plugins. If you see "Safe Mode" in the title:


  1. Click the power icon
  2. Select "Restart OctoPrint" (not safe mode)
  3. Wait for normal restart


Is the plugin up to date?


Settings > Software Update - check for SimplyPrint updates.


Check internet connection


The Pi needs internet access. If OctoPrint works locally but SimplyPrint is offline, check your network.



3. USB and cable issues


If your printer is disconnected in both OctoPrint and SimplyPrint, the problem is between OctoPrint and your printer.


First: Try power cycling your printer (turn off, wait 30 seconds, turn on).


3.1 USB cable problems


Important: 9 out of 10 connection issues are caused by the USB cable.


Problem

How to spot it

Solution

Charge-only cable

Thin, cheap cable

Use a data cable

Damaged cable

Intermittent connections

Replace it

Wrong connector

Doesn't fit right

Check printer's USB type


USB connector types:


Connector

Common printers

USB-B (square)

Prusa i3 MK3/S/+, Ultimaker 2

Mini USB

Creality Ender 3/Pro, CR-10

Micro USB

Prusa Mini

USB-C

Prusa MK4/XL, Ender 3 S1


Tip: A short, quality USB cable often fixes connection problems. Cables with ferrite cores (cylindrical bumps) help reduce interference.


3.2 Prusa printers: RPi port setting


Prusa MK3, MK3S, MK3S+, or Mini users: Check this setting!


Prusa printers have an "RPi port" setting that blocks normal USB connections.


To fix:

  1. On printer screen: Settings
  2. Find RPi port
  3. Set to off


3.3 Other USB fixes


  • Try a different USB port on the Pi
  • Remove USB hubs - connect directly
  • Power cycle the printer
  • Remove SD card from printer



4. Raspberry Pi issues


4.1 Power supply


Bad power causes random disconnections.


Signs of power problems:

  • Lightning bolt icon in OctoPrint
  • Random disconnections
  • Pi freezing or rebooting


Fix: Use official Raspberry Pi power supply (5V, 3A for Pi 4). Avoid phone chargers.


4.2 Can't access OctoPrint?


  1. Wait for Pi to finish booting (few minutes after power on)
  2. Check you're on the same network
  3. Try pinging: ping <pi-ip-address>



Works well:

  • Raspberry Pi 4B (2GB+)
  • Raspberry Pi 5
  • Raspberry Pi Zero 2 W


Not recommended:

  • Raspberry Pi Zero W (original) - too slow
  • Raspberry Pi 2 - underpowered



Getting help


Gather this first


  1. OctoPrint version
  2. SimplyPrint plugin version
  3. Raspberry Pi model
  4. Printer model
  5. Screenshot of OctoPrint connection panel


Support




Something unclear or missing in this guide? Let us know on Discord.





Updated on: 09/01/2026

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