K2 Pro Combo CFS - FR2865 / “retrude error, failed to exit connections” during filament change and final unload

Flagship K Series Creality Flagship K2 Pro & K2
1

Hello everyone.

I recently purchased a Creality K2 Pro Combo with CFS, and the printer has been in use for about one week. Unfortunately, I am experiencing recurring filament unload/retraction failures related to the CFS.

The main error shown in Creality Print is:

FR2865: Feed issue, filament failed to exit extruder.

This usually happens at the end of the print, around 99%, when the printer tries to unload/retract the filament after the print is already completed.

However, I also noticed that the issue is not limited to the final unload. It also happens during filament changes. I tried printing a black and white part using the CFS, and the printer keeps stopping during the filament change process.

I checked the Fluidd console and found these messages during the failures:

“retrude error, failed to exit connections”, values: [1, “B”]

and later:

“retrude error, failed to exit connections”, values: [1, “A”]

Before the error, the console also shows messages like:

“cut sensor detected”

“cut to return OK”

So it seems that the cutter/sensor step may be detected correctly, but the failure happens during the filament return/retraction process through the CFS path.

Current observations:

  • Printer: Creality K2 Pro Combo

  • System: CFS

  • Material: PLA

  • Printer is new, about one week of use

  • Error in Creality Print: FR2865

  • Error in Fluidd: “retrude error, failed to exit connections”

  • Failure happened on at least CFS slot 1A and 1B

  • The issue happens at the end of prints and also during filament changes

  • The CFS sometimes seems to tension or jam the filament

  • Sometimes I find filament in the extruder area after opening/checking it, but other times I do not, which makes the diagnosis confusing

  • When using the external/side spool holder, some tests seem to work better, which makes me suspect the CFS, buffer, PTFE path, cutter/sensor, extruder, or firmware retraction routine

I already contacted Creality support and a ticket was opened, but I would like to know if other K2 Pro Combo users have experienced the same issue.

Has anyone seen this FR2865 error or the Fluidd message “retrude error, failed to exit connections” on the K2 Pro Combo?

If yes, what solved it for you?

Possible areas I am trying to investigate:

  • CFS spool tension

  • CFS slot feeding/retraction

  • Buffer problem

  • PTFE tube path resistance

  • Cutter or cut sensor issue

  • Extruder filament detection issue

  • Firmware/macro issue during final unload or filament change

  • Filament spool compatibility or drag inside the CFS

Any advice would be appreciated. The printer is new, and the experience has been very frustrating because the CFS is one of the main reasons I bought the Combo version.

2

Whats the humidity level in the CFS?

3

hello the its 41%

4

I would definitely add “Wet Filament” to your possible areas to investigate. That is very high. I would put that at the top of your “trying to investigate” pile. Whether now or later, you’ll need to get that number down to at least low teens if not single digits.

5

Hi Fabrício,

Welcome to the community! Don’t get discouraged—the K2 Pro and CFS combo is an incredible machine, but multi-material setups have tight tolerances, and you are looking in the exact right places.

The Fluidd error message combined with the FR2865 code tells us something very specific: The printer’s toolhead successfully cuts the filament, but when the CFS internal motor attempts to pull the remaining strand back up the long Bowden line, it meets too much mechanical resistance (friction) and times out, thinking there is a jam.

While the previous comment mentioned humidity (and it’s true, 41% inside a closed CFS is a bit high and can make PLA slightly brittle or swollen), a mechanical restriction in the path is usually the primary trigger for this specific retraction timeout.

Here are the top areas to check to resolve this, including a hidden issue that fixed this exact error on my own machine:

  1. Hidden Filament Debris in the Extruder: I ran into this exact same error code, and the culprit turned out to be a tiny, broken-off piece of filament hiding inside the extruder assembly. Even if the path looks clear at first glance, a small fragment can act like a one-way check valve—letting filament feed forward smoothly, but completely wedging and blocking the strand the moment the CFS tries to retract it. It is highly recommended to open up the extruder interface and check for any hidden debris.

  2. The Filament Tip Shape: When the toolhead cuts the filament, sometimes a tiny, slightly bulbous string or “pigtail” is left on the end of the strand. If the filament path has a sharp bend, that bulbous tip gets wedged. Check the retracted ends of your spools—if they have a thick blob on the tip, you may need to slightly adjust your flush/retraction cooling moves or ensure your cutter blade is perfectly sharp and fully seating.

  3. PTFE Tube Bending Radius: Look closely at the path your PTFE tube takes from the buffer on the back of the printer up to the toolhead. If there are any sharp loops, tight curves, or places where the tube kinks during a filament change, it creates immense drag. Try straightening the path or using a printed guide to keep the radii smooth.

  4. CFS Hub / Internal Buffer Tension: Sometimes the internal spring tension in the rear buffer block is a little too tight out of the box, causing the CFS to think a stuck spool has occurred when it’s really just fighting a stiff buffer spring during the initial pull-back phase. Make sure the small slider assembly on the back moves freely without binding.

Since you already have a ticket open with Creality support, checking the extruder for hidden fragments and smoothing out that PTFE line are your best immediate steps to get your multi-color prints running smoothly.

Let us know if clearing out the extruder or straightening the tube path fixes it for you!

MAC486

6

Thank you everyone for the suggestions. I would like to provide a complete update, because the problem is continuing and I am trying to understand whether this is a known K2 Pro Combo/CFS issue or a defective component in my unit.

My printer is a new Creality K2 Pro Combo with CFS, and I have been using PLA / Creality Hyper PLA. Since the first days of use, I have experienced repeated filament feeding, retraction and clogging failures when printing through the CFS.

Creality support asked me to check whether the filament is actually being cut when error 2865 occurs. In my case, I can confirm that the filament is being cut in many of the failures. I also calibrate the printer before every print. However, even after the filament is cut, the CFS frequently fails to retract or feed it correctly.

I reviewed the Klippy and Moonraker logs from May 25 to May 30. The logs show repeated errors such as:

  • extrude error, maybe it's blocked at the connections;

  • extrude error, maybe there's a blockage between the connections and the filament sensor;

  • the nozzle is blocked;

  • empty printing, box speed is smaller than extruder;

  • empty printing, material enwind;

  • retrude error, failed to exit connections;

  • extrude error, extrude but not trigger buffer full limit;

  • some cut position error records.

At the same time, the logs show 273 records of [box] cut to return OK. This is why I do not believe the issue is simply that the cutter is not operating. The printer often confirms a successful cut, but then I still get feeding, retraction, buffer or hotend blockage failures.

The most serious examples were:

  • During a long print on May 28, the printer registered an extrusion error involving a possible blockage between the connections and the filament sensor. Later in the same print, it registered empty printing, material enwind, and that failure remained active for almost one hour.

  • On May 29, during the same long print, the log repeatedly registered empty printing, box speed is smaller than extruder for many hours.

  • On May 30, during another print, the printer warned that it appeared to be printing without extrusion. I visually confirmed that the toolhead was moving in the air without depositing any filament. The physical part stopped receiving material at approximately layer 318, but the print continued advancing until approximately layer 344 before I paused it. The part was lost.

When a clog happens, I usually find filament accumulated or blocked mainly in the hotend area. I have already had to disassemble the extruder approximately 10 times to remove jammed filament and restore operation. This is extremely frustrating for a new printer.

Another important detail: I have previously managed to print successfully using the external spool holder, while these recurring failures are happening mainly when using the CFS.

My print history already shows at least 14 failed or interrupted jobs, representing approximately 58 hours of recorded print time. Some were short troubleshooting attempts, but others were long prints lost after many hours.

At this point, I am trying to understand whether other K2 Pro Combo users have experienced the same combination of symptoms:

  1. CFS cutting the filament successfully but failing during retraction or feeding afterwards;

  2. repeated hotend clogs caused during CFS use;

  3. empty printing errors where the printer continues moving without extrusion;

  4. prints working from the external spool holder but failing through the CFS;

  5. buffer, hub, PTFE, extruder sensor or CFS motor problems causing these symptoms.

For anyone who has experienced this: what component was ultimately responsible in your case? Was it solved by replacing the CFS hub, buffer, PTFE tubes, extruder sensor, hotend, cutter assembly, or the complete CFS?

I do not want to keep disassembling the extruder or replacing random parts without identifying the actual root cause. Any experience from other K2 Pro Combo owners would be greatly appreciated.

7

Yes, I am also randomly experiencing two similar symptoms.

#1 - failed retraction
During a filament change, the cut appears successful, but the retract is not and an error is thrown.
When I open the extruder, there is usually a small melted blob of plastic on the end that prevents proper retraction because the end is now larger than the PTFE tube opening. This causes the retraction step to fail, or the filament to break.

Unfortunately, I have not figured out why this is happening yet - or a proper solution.

#2 - Air printing error
I have noticed this is typically triggered when a corner of a print loses adhesion and warps resulting in a high spot. The nozzle starts scraping the print and the plastic can’t get out of the nozzle, then the extruder gear grinds a flat spot on the filament and can’t advance. The result is “air printing”. Eventually, the printer throws the “empty printing” error and pauses.