A broken or non-existent connection between OctoPrint and an Ender 3 is a common issue most people face. It can lead to the printer not connecting to and accepting prints, or low-quality prints.
This article will walk you through some different methods that have worked for real users on how to get this issue fixed.
Why Does my Ender 3 Not Connect to OctoPrint
Besides, you can’t use OctoPrint remotely or its intended purpose if it is not connecting to the printer. Here are some things that can lead to these issues:
Faulty USB cable
Wrong Port and Baud rate Settings
EMI Interference
Malfunctioning Plugins
Low latency Mode enabled
Poor power supply
Wrong Wi-Fi settings
Turned off PSU
Buggy Linux packages
Missing drivers
Unsupported plugins
How to Fix an Ender 3 That Won’t Connect to OctoPrint
Here’s how to fix an Ender 3 that won’t connect to OctoPrint:
Restart the Raspberry Pi
Replace your USB B cable
Correct your baud rate and port settings
Ground your Pi board
Run OctoPrint in safe mode
Disable low latency mode
Use a proper power supply
Check the Pi’s Wi-Fi settings
Turn on your printer
Remove Brltty from Linux
Install Creality temperature plugin
Install the proper drivers
Install compatibility plugin
1. Restart The Raspberry Pi
One of the first things I’d try when your Ender 3 doesn’t connect to OctoPrint is to do a quick power cycle of the Raspberry Pi. This is especially good if your Pi was working before without issues.
Simply shut down the Raspberry Pi, disconnect it from the power source and leave it off for five minutes. After five minutes, power it on and see if it can connect properly to your printer.
Note: Never power off your printer while your Pi is still connected. This will cause the Raspberry Pi to back-power the 3D printer’s board which can lead to a whole host of other issues.
2. Replace Your USB-B Cable
Charging a faulty USB cable is one of the most common fixes for an OctoPrint that won’t connect to an Ender 3. This happens because most of the newer Ender 3 models (Pro and V2) use a Micro USB instead of a USB B cable.
Most Micro USB cables are only meant for power transfer, not for data transfer. So, when you use them with your printer and OctoPrint, no data is getting transferred to the printer.
One user who tried three cables found that none of them were data cables. He found another cable he had lying around and it worked perfectly fine since it turned out to be a data cable. He can now control his 3D printer using OctoPi as it’s supposed to work.
Another user also had this issue with their Raspberry Pi, having trouble selecting any Serial port apart from the Auto port on OctoPrint.
At this point, OctoPi will display this message due to the faulty cable:
State: Offline (Error: No more candidates to test, and no working port/nauseate combination detected.)
To fix this, make sure you get a good USB cable that’s properly rated for data and power transfer. If you have any cameras lying around, you can try using their USB cable.
The Baud Rate and Port Settings detect and control where and how much data is transferred between the printer and the Pi. If these settings are wrong, the Pi simply won’t connect to the 3D printer.
Most times, these settings are on Auto and they do a good job of detecting the correct value. However, they can sometimes be filled with the wrong values.
For example, one user’s OctoPrint determined that their Baud Rate was 9600 which was the wrong value for an Ender printer.
So, most people recommend leaving the Port setting on Auto. The Pi will automatically cycle through all its ports until it finds the one connected to the 3D printer.
For the Baud rate, most people recommend setting it to a value of 115200 for Ender 3 printers. This value has been proven to work for almost all Ender printers. The user who had the issue said that this value worked for her.
4. Ground Your Pi Board
Some people have fixed their Ender 3 connection to OctoPrint by grounding their Raspberry Pi.
Grounding your Pi helps get rid of electromagnetic interference (EMI) that can ruin your connection and your print. EMI happens because both your Pi board and the 3D printer’s stepper drivers produce EMI noise that can interfere with their communication.
This can lead to the Pi board sending error messages and illegible commands to your printer. These commands can either break their connection or result in a bad print.
One user noticed that he was getting poor prints through his Pi, so he checked his logs. In the logs, he saw some unintelligible symbols mixed in with the proper G-Code, causing the issue.
To fix this, he grounded his Raspberry Pi by powering it through the printer’s power supply. This reduced the noise as they both had the same ground.
You can follow the video below to learn how to power your printer through an Ender 3’s power supply.
This will help convert the PSU’s 12 or 24V to the 5V needed to power the Raspberry Pi. You can check out this video for tips on how to install it.
Another thing to check out is the ribbon cable that connects the mainboard to the screen. Another user found out that they were having problems due to the way their ribbon cable was folded.
The ribbon cable is not shielded, so if the cable is folded, it can lead to EMI interference. To fix this, make sure the cable is straight at all times and it isn’t folded on itself.
He found that after adjusting his ribbon cable, all the errors he had gone away. The amount of resend requests went from 16% down to 0% and some print imperfections went away.
5. Run OctoPrint in Safe Mode
Running OctoPrint in safe mode disables all third-party plugins when you reboot your OctoPrint. This enables you to troubleshoot the Pi and determine if any plugin is behind the connection issues.
Safe mode is very helpful because new versions of plugins and firmware can be responsible for connection issues. So, when you disable them, you can easily check the logs to see what is responsible for what.
One plugin most users say is responsible for connectivity issues is the MeatPack plugin. A user said that he had to uninstall the MeatPack plugin before his OctoPrint started working. Someone also confirmed that it worked for him on his Ender 3 Pro, along with an SKR Mini E3 V2 board.
Another user said that he decided to install the MeatPack plugin and that actually caused his connection to die. He uninstalled it and it fixed the connectivity from the OctoPi on his RPi 3+ with the Ender 3.
One user connected to OctoPrint using safe mode and that’s how he figured out that the MeatPack plugin was the issue.
Other plugins of note that have caused connection problems for users include:
OctoPrint Automatic Shutdown plugin
Tasmota plugin
To run OctoPrint in safe mode, click on the Power icon on the dashboard. In the menu that appears, select Restart OctoPrint in Safe Mode.
6. Disable Low Latency Mode
Disabling Low latency mode can help fix connection issues between your 3D printer and your Pi. It is a connection option that tries to set a low latency mode on the serial port.
As one user experienced, if it is not successful, it returns an error that leads to a terminated connection. To turn it off, click on the spanner icon to open the settings menu.
In the settings menu, click on Serial Connection > General > Connection. Scroll down until you see Request Low Latency mode on the serial port. Uncheck the box if it is ticked.
7. Use a Proper Power Supply
A proper power supply keeps your Raspberry Pi from shutting down intermittently, especially during long prints. This happens because components like the Wi-fi card and the SD card consume a lot of power.
If you see the red light on your Raspberry Pi blinking, this is a sign that the board isn’t getting enough power.
So, you should always use a proper power supply to avoid the Pi shutting down the connection randomly. For Pi models 3 upwards, Raspberry recommends using a charger rated at least 3A/5V.
You should try getting the official Raspberry Pi 4 Power Supply to power the Raspberry Pi board properly. It has a really high rating of 4.8/5.0 at time of writing and many people state how reliable it is.
8. Check the Pi’s Wi-Fi Settings
You need to enter the details of the Wi-Fi connection properly in your Pi for it to have a successful connection to the network. If the details aren’t correct, you won’t even be able to log in to OctoPi in your browser.
To fix this, you first have to check if your OctoPi is connected to your Wi-Fi. While your Pi is on, log in to your router and check all the devices connected to see if your Pi is among them.
If your Pi isn’t there, then you might’ve gotten the Wi-fi settings wrong. You’re going to need to re-flash Pi on your SD card to fix the error.
You can check out the video below to see how to set up your Wi-Fi properly on your Raspberry Pi.
9. Turn On Your Printer
This sounds like a strange fix, but check if your printer is switched on while your Raspberry Pi is connected to it. This is because back power can sometimes produce the illusion of the printer being on without it being on.
If the Raspberry Pi is plugged into the printer’s USB port and turned on, the printer’s board will receive power from the Pi. In some cases, the printer’s LED will light up, producing the illusion of being on.
One user ran their printer for a while without realizing that it was on. The printer was struggling to heat up and move due to the low power being provided through the Pi board.
This is very dangerous as it can ruin both the Pi board and the 3D printer’s board. Luckily, they noticed the switch on the printer’s PSU wasn’t on and they switched it back on, resolving the issue.
10. Remove Brltty on Linux
Another potential fix for your Ender 3 not connecting to OctoPrint is to remove BrItty.
If you’re running OctoPrint on a Linux Pc, Ubuntu specifically, you might need to remove Brltty since this application can interfere with your USB ports making it difficult to connect to the printers via OctoPrint.
Brltty is an accessibility application that helps disabled people using braille devices to access the Linux console. It can interfere with USB serial ports, so to stop this, you have to remove the package.
A user discovered this when they saw OctoPrint worked on their Windows Installation but not Linux. It only started working after they removed Brltty. Many other users have confirmed this fix as well.
He said he spent a few days wiping and reinstalling both Ubuntu and OctoPrint, even changing his BIOS settings. What worked for him was to remove the brItty package.
You can do this by running the command and rebooting it afterwards:
sudo apt autoremove Brltty
11. Install the Creality Temperature Plugins
Some users have reported that installing the Creality-2x-temperature-reporting-fix plugin fixes their connection issues with their 3D printer.
Due to glitches in some versions of OctoPrint, if this driver isn’t installed in OctoPrint, it won’t work for Creality printers.
If your printer is throwing an error message about temp reporting, especially after you’ve just connected to the printer, then you need the plugin. Just go down to the OctoPrint plugin manager in the settings and install it.
12. Install The Proper Drivers
If you’re running OctoPrint on a Windows PC instead of a Raspberry Pi, you’re going to want to install drivers for the Ender 3. Without the Ender 3 drivers, the printer won’t be able to communicate with the PC and use OctoPrint.
For example, one user was trying to connect an Ender 3 to a Windows machine using Linux port names. It didn’t work until they installed the proper Windows drivers for the Ender 3.
You can download the drivers for Creality printers here. Once you download it, just unzip the file and install the drivers.
If you have a V1.1.4 board, then the drivers you should install are the CH340 Driver.
13. Install Compatibility Plugin
This fix isn’t Ender 3 specific, but it might be helpful to those using other brands. Printer brands like Makerbot and Flashforge aren’t supported by OctoPrint right out of the box.
For them to work with and connect to the 3D printer, you have to install a special plugin called GPX. This plugin adds support for Makerbot, Monoprice, Qidi, and Flashforge printers so they can communicate properly with OctoPrint.
One user who has a Qidi Tech 3D printer said he was having connection issues and used it to solve the problem.
Connection issues between an Ender 3 and OctoPrint can be quite frustrating. However, if you apply the fixes above, you should have both of them up and running in no time at all.
Michael Dwamena is the founder of 3D Printerly, a platform dedicated to simplifying 3D printing for hobbyists and professionals alike. Owns over 20 3D printers (filament and resin) and has plenty experience 3D printing. Michael has authored over 900 articles, helping millions navigate the exciting world of 3D printing.
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