# Mcu 'mcu': Unable to connect Neptune 3 Pro **URL:** \ **Category:** General Discussion\ **Created:** [February 24, 2025, 5:31pm UTC](https://klipper.discourse.group/t/mcu-mcu-unable-to-connect-neptune-3-pro/22198 "2025-02-24T17:31:53Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![mudkip](https://avatars.discourse-cdn.com/v4/letter/m/22d042/32.png) [@mudkip](https://klipper.discourse.group/u/mudkip)\ **Post date:** [February 24, 2025, 5:31pm UTC](https://klipper.discourse.group/t/mcu-mcu-unable-to-connect-neptune-3-pro/22198/1 "2025-02-24T17:31:53Z")
### Basic Information: Printer Model: Elegoo Neptun 3 Pro Host / SBC: Raspberry pi 3b+ [printer.cfg](https://klipper.discourse.group/uploads/short-url/9WgydmN3Wjpysln1Le8INUGb2QV.cfg) (4.7 KB) [klippy (2).log](https://klipper.discourse.group/uploads/short-url/nfUxWnPqyn6Oi3OCwLXYPDhHMnp.log) (14.5 KB) Everything was working on these settings before. A little backstory: I had a clogged nozzle and when I cleaned it, the SBC stopped seeing the printer. I tried to reflash everything, but it didn’t help. Now it writes the following error: mcu ‘mcu’: Unable to connect I Tried: 1. Reflash the Raspberry PI 2. Reflash the printer (configured the firmware file, named it differently than in the previous firmware downloaded to SD, inserted into the printer, turned on the printer, waited for a while, then restarted the printer and connected the cable to the Raspberry ). 3. Replace the cable. Please help to solve this problem. ---
**Author:** ![system](https://global.discourse-cdn.com/free1/uploads/klipper/original/1X/64419bf2aac6639e6ef5cef200dcd456b0a01ac3.png) [@system](https://klipper.discourse.group/u/system)\ **Post date:** [April 25, 2025, 5:32pm UTC](https://klipper.discourse.group/t/mcu-mcu-unable-to-connect-neptune-3-pro/22198/2 "2025-04-25T17:32:02Z")
This topic was automatically closed 60 days after the last reply. New replies are no longer allowed.