# Unable to connect to MCU after April 4, 2024 Klipper update **URL:** \ **Category:** General Discussion\ **Created:** [April 9, 2024, 6:45pm UTC](https://klipper.discourse.group/t/unable-to-connect-to-mcu-after-april-4-2024-klipper-update/15634 "2024-04-09T18:45:09Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![dilectus](https://avatars.discourse-cdn.com/v4/letter/d/7ba0ec/32.png) [@dilectus](https://klipper.discourse.group/u/dilectus)\ **Post date:** [April 9, 2024, 6:45pm UTC](https://klipper.discourse.group/t/unable-to-connect-to-mcu-after-april-4-2024-klipper-update/15634/1 "2024-04-09T18:45:10Z")
### Basic Information: Printer Model: Creality CR-10 Smart Pro MCU / Printerboard: 2 X Creality CR-FDM-v2.5.S1\_100 (one is “mcu”, the other is “auxmcu”) + Raspberry Pi Pico as mcu “pico” Host / SBC: x86\_64 PC 64bit Debian GNU/Linux 11 (bullseye), kernel version Linux 5.10.0-28-amd64 [klippy.log](https://klipper.discourse.group/uploads/short-url/agb3vadKHLZZixfOrOr8Q3Snoau.log) (1.6 MB) ### Describe your issue: Unable to connect to mcu: “mcu” after April 4, 2024 Klipper update. Unsuccessful actions taken: Klipper restarts. Firmware restarts. Host restarts. Checked all physical connections. Disconnected all MCU’s and host from power for 30 minutes. Updated all 3 MCU’s to the latest Klipper firmware as of April 4, 2024 - error persisted. Successful actions taken: Using KIAUH, rolled back Klipper to 1 commit prior to April 4, 2024 returned printer to normal function. Also, attempting to update Klipper today to the latest commits dated April 5, 2024 produced the same issue and rolling Klipper back now 2 commits resolved the issue as before. I seem not to be able to update Klipper past commits dated April 3, 2024 without this issue reoccurring. Any help would be greatly appreciated. Thanks! 🙂 ---
**Author:** ![TheFuzzyGiggler](https://yyz2.discourse-cdn.com/free1/user_avatar/klipper.discourse.group/thefuzzygiggler/32/12313_2.png) [@TheFuzzyGiggler](https://klipper.discourse.group/u/TheFuzzyGiggler)\ **Post date:** [April 10, 2024, 1:12pm UTC](https://klipper.discourse.group/t/unable-to-connect-to-mcu-after-april-4-2024-klipper-update/15634/2 "2024-04-10T13:12:04Z")
You’ve got an i2c error in there that I don’t know what caused it, but you’ve also got the manual\_stepper error I corrected in another post. See here and follow the directions to drop the file in your ~klipper/klippy/extras… > [@Mainsail doesn't connect to Moonraker after Klipper update](https://klipper.discourse.group/t/mainsail-doesnt-connect-to-moonraker-after-klipper-update/15641/6): > > [manual\_stepper.zip](https://klipper.discourse.group/uploads/short-url/7aPjLAcPIIgD8Za1MlARo32fWbv.zip) (1.8 KB) Okay, dealers choice, the previous one reverts back to before the change. This one actually corrects the issue. @koconnor - Sorry for the double tag, but I can confirm the newest update to manual\_stepper (the status function) causes Mainsail to hang when the webhooks try to get the stepper status cause there is an error. I’ve messed with my branch of Klipper so don’t want to put in a PR and have to mess with another branch and making sure I take out unintentional … @Sineos & @EddyMI3D - Don’t know if you want to let other people make sure my fix works and then maybe make a sticky? Manual\_stepper.py is broke after the 4/4/23 update to Klipper if anyone has a [manual\_stepper] defined. I updated my Klipper and confirmed it does cause Mainsail to get stuck in an “Initialization” loop because the webhook doesn’t return a value from the status call to manual\_stepper because the function had an error. I bet there is going to be a lot of people asking why they can’t connect after the update (I’ve seen two so far). I tagged Kevin in the linked post to give him the heads up. ---
**Author:** ![koconnor](https://avatars.discourse-cdn.com/v4/letter/k/aca169/32.png) [@koconnor](https://klipper.discourse.group/u/koconnor)\ **Post date:** [April 10, 2024, 2:49pm UTC](https://klipper.discourse.group/t/unable-to-connect-to-mcu-after-april-4-2024-klipper-update/15634/3 "2024-04-10T14:49:01Z")
Unfortunately, there was a defect in PR #6527. I reverted that PR in commit 4cfa266e. Sorry for the delay. -Kevin ---
**Author:** ![dilectus](https://avatars.discourse-cdn.com/v4/letter/d/7ba0ec/32.png) [@dilectus](https://klipper.discourse.group/u/dilectus)\ **Post date:** [April 11, 2024, 7:28pm UTC](https://klipper.discourse.group/t/unable-to-connect-to-mcu-after-april-4-2024-klipper-update/15634/4 "2024-04-11T19:28:29Z")
Thank you !!! 😃 ---
**Author:** ![system](https://global.discourse-cdn.com/free1/uploads/klipper/original/1X/64419bf2aac6639e6ef5cef200dcd456b0a01ac3.png) [@system](https://klipper.discourse.group/u/system)\ **Post date:** [June 10, 2024, 7:29pm UTC](https://klipper.discourse.group/t/unable-to-connect-to-mcu-after-april-4-2024-klipper-update/15634/5 "2024-06-10T19:29:15Z")
This topic was automatically closed 60 days after the last reply. New replies are no longer allowed.