Hi
I have Shelly Plus 1PM Gen3. I have successfully installed Tasmota via OTA (mgos) and started to config it.
BUT when I restarted it once then it was not possible to get Tasmota web access anymore. Just “Not found”. Even It forgot WiFi credentials and SSID name “ShellyPlus1PM-….” returned back.
Is there any way to re-flash Tasmota again with serial UART adapter or is it bricked forever?
You should be able to flash the minimal Tasmota build it and retry your next steps. The device might be running out of memory, but I’m not aware of specific issues with those devices, meaning, I haven’t seen this on this forum.
Where I used Tasmota it was with Sonoff. I’ve so far stuck with the Shelly firmwares.
I did not find any guide about serial flashing of this device. I was not successful with common steps (UART programmer - 3v3, rx, tx, gnd) which i use with Sonoff devices.
Did you connect via the header?
I did. It was not responding any way.
This is the correct model site
I’ve bricked a few Shelly 1 Plus devices with the same issue. Runs tasmota, then within 10 mins restarts with the old Shelly SSID, and webpage saying Not Found. I’d love to know what’s actually going on.
Same for me. In my case I’ve changed Tasmota template and after restart all tasmota content and SSID wiped out. Just “Not Found”.
Has anyone had any luck with a serial flash recently?
I’ve got a batch of Gen 3 Shelly 1 (the standard blue version, not the PM Shelly 1 Gen3) and just can’t get the flash to fully comelete and work following a reboot. I’ve successfully connected following the method I’ve used for years (lots of shelly one, shelly 2.5, dimmers, RGB etc etc mostly gen 1 and gen 2 devices), this is connecting UART via the exposed pin headers and using ESPflasher or Tasmotizer to deliver the package.
For some reason with these new Gen 3 devices I’ve had no success. I’ve tried the Tasmota lite version, tried the BIN files, and tried the GZ files but not luck.
Anyone know what specific tasmota version is needed for the initial flash on these devices?
Is your flasher still working properly?
Often, flashing issues are due to insufficient power or incorrect wiring. I’ll assume that the latter isn’t an issue, since you’ve done this before.
Also, what exactly is the issue? Do you have logs or debug output of sorts? After flashing, is the device bricked or does it still have the Shelly firmware on it?
Last time I tried flashing something with Tasmota (it was a Sonoff, as I run stock firmware on my Shellys) was last year, and I just couldn’t get the latest Tasmota (8.x, I think) running, not even the lite, so I just flashed it with ESPHome.
Hi, thanks for the response. I did doubt the flasher so bought a new one and the results are exactly the same. Flash commences with an estimated time of 78s then in each case it finished ~ 10-15s early. All logs report flash complete but the devices do not boot into Tasmota, everything remains Shelly stock.
‘’’
######2025-08-23######
#######0.04.009#######
######FLASH INFO######
BIN file: tasmota32 (1).bin
COM port: (COM8) FTDI USB Serial Port (REGISTRY_INFORMATION_ARRAY_n2_2)
Baud rate: 115200
######POST FLASH######
No post flash information entered…
######FLASH LOG######
[esptool.exe -vv -cd nodemcu -cb 115200 -cp COM8 -ca 0x00000 -cf “C:\Users\geoff\Documents\Nextcloud\Sync\Software\esp easy\bin\tasmota32 (1).bin”]
[23/08/2025 17:36:47] esptool v0.4.12 - (c) 2014 Ch. Klippel [email protected]
[23/08/2025 17:36:47] setting board to nodemcu
[23/08/2025 17:36:47] setting baudrate from 115200 to 115200
[23/08/2025 17:36:47] setting port from to COM8
[23/08/2025 17:36:47] setting address from 0x00000000 to 0x00000000
[23/08/2025 17:36:47] espcomm_upload_file
[23/08/2025 17:36:47] espcomm_upload_mem
[23/08/2025 17:36:47] setting serial port timeouts to 1000 ms
[23/08/2025 17:36:47] opening bootloader
[23/08/2025 17:36:47] resetting board
[23/08/2025 17:36:47] trying to connect
[23/08/2025 17:36:47] flush start
[23/08/2025 17:36:47] setting serial port timeouts to 1 ms
[23/08/2025 17:36:47] setting serial port timeouts to 1000 ms
[23/08/2025 17:36:47] flush complete
[23/08/2025 17:36:47] espcomm_send_command: sending command header
[23/08/2025 17:36:47] espcomm_send_command: sending command payload
[23/08/2025 17:36:47] espcomm_send_command: receiving 4 bytes of data
[23/08/2025 17:36:47] espcomm_send_command: receiving 4 bytes of data
[23/08/2025 17:36:47] espcomm_send_command: receiving 4 bytes of data
[23/08/2025 17:36:47] espcomm_send_command: receiving 4 bytes of data
[23/08/2025 17:36:47] espcomm_send_command: receiving 4 bytes of data
[23/08/2025 17:36:47] espcomm_send_command: receiving 4 bytes of data
[23/08/2025 17:36:47] espcomm_send_command: receiving 4 bytes of data
[23/08/2025 17:36:47] espcomm_send_command: receiving 4 bytes of data
[23/08/2025 17:36:47] Uploading 2108224 bytes from C:\Users\geoff\Documents\Nextcloud\Sync\Software\esp easy\bin\tasmota32 (1).bin to flash at 0x00000000
[23/08/2025 17:36:47] erasing flash
[23/08/2025 17:36:47] size: 202b40 address: 000000
[23/08/2025 17:36:47] first_sector_index: 0
[23/08/2025 17:36:47] total_sector_count: 515
[23/08/2025 17:36:47] head_sector_count: 16
[23/08/2025 17:36:47] adjusted_sector_count: 499
[23/08/2025 17:36:47] erase_size: 1f3000
[23/08/2025 17:36:47] espcomm_send_command: sending command header
[23/08/2025 17:36:47] espcomm_send_command: sending command payload
[23/08/2025 17:36:47] setting serial port timeouts to 18972 ms
[23/08/2025 17:36:47] setting serial port timeouts to 1000 ms
[23/08/2025 17:36:47] espcomm_send_command: receiving 4 bytes of data
[23/08/2025 17:36:47] writing flash
[23/08/2025 17:36:55] … [ 3% ]
[23/08/2025 17:37:03] … [ 7% ]
[23/08/2025 17:37:11] … [ 11% ]
[23/08/2025 17:37:19] … [ 15% ]
[23/08/2025 17:37:27] … [ 19% ]
[23/08/2025 17:37:35] … [ 23% ]
[23/08/2025 17:37:43] … [ 27% ]
[23/08/2025 17:37:51] … [ 31% ]
[23/08/2025 17:37:59] … [ 34% ]
[23/08/2025 17:38:07] … [ 38% ]
[23/08/2025 17:38:15] … [ 42% ]
[23/08/2025 17:38:23] … [ 46% ]
[23/08/2025 17:38:32] … [ 50% ]
[23/08/2025 17:38:40] … [ 54% ]
[23/08/2025 17:38:48] … [ 58% ]
[23/08/2025 17:38:56] … [ 62% ]
[23/08/2025 17:39:04] … [ 66% ]
[23/08/2025 17:39:12] … [ 69% ]
[23/08/2025 17:39:20] … [ 73% ]
[23/08/2025 17:39:29] … [ 77% ]
[23/08/2025 17:39:37] … [ 81% ]
[23/08/2025 17:39:45] … [ 85% ]
[23/08/2025 17:39:53] … [ 89% ]
[23/08/2025 17:40:02] … [ 93% ]
[23/08/2025 17:40:10] … [ 97% ]
[23/08/2025 17:40:17] … [ 100% ]
[23/08/2025 17:40:17] starting app without reboot
[23/08/2025 17:40:17] espcomm_send_command: sending command header
[23/08/2025 17:40:17] espcomm_send_command: sending command payload
[23/08/2025 17:40:17] espcomm_send_command: receiving 4 bytes of data
[23/08/2025 17:40:17] closing bootloader
[23/08/2025 17:40:17] flush start
[23/08/2025 17:40:17] setting serial port timeouts to 1 ms
[23/08/2025 17:40:17] setting serial port timeouts to 1000 ms
[23/08/2025 17:40:17] flush complete
[2025-08-23 17:40:17] DONE!
############################
[2025-08-23 17:40:17] The COM port was already in use… the post-flash did not complete.
[2025-08-23 17:40:17] JOB COMPLETED, over and out!
‘’’
I have honestly no idea.
Maybe you can try a lower baud rate, even though there doesn’t seem to be any errors.
