QUERY · ISSUE

mpremote: Writing fails when using mount and using multibyte characters.

openby sebromeroopened 2023-11-23updated 2026-01-10

bugtoolsunicode

I'm on MicroPython v1.21.0 on 2023-10-06; PORTENTA with STM32H747
The following script runs fine when executing it on the board e.g. mpremote connect id:3871345 run ./examples/demo.py

with open("foo.txt", 'w', encoding='utf-8') as file:
    file.write("🔢 Data" + '\n')
    file.write("🔢 Data" + '\n')

with open("foo.txt", 'r', encoding='utf-8') as file:
    data = file.read()
    print(data)

It correctly prints

🔢 Data
🔢 Data

However, when running it after mounting the current directory, it fails. e.g. mpremote connect id:387134 mount . run ./examples/demo.py

It prints

Local directory . is mounted at /remote
ta
ta
🔢 Da🔢 Da

Please note that the ta output is created by the write() function which shouldn't produce any output to the console.

If I modify the above example to write the following data, it stalls:
file.write("🔢 Data" + '\n' + "🔢 Data")

Looks like an issue with how multi byte characters are handled when using mount.

CANDIDATE · ISSUE

Unable to print unicode characters when running repl with mpremote

openby XuanTongYaoopened 2024-06-08updated 2026-01-10

bugtoolsunicode

Port, board and/or hardware

RP2 Pico

MicroPython version

MicroPython v1.22.1 on 2024-01-05; Raspberry Pi Pico with RP2040

Reproduction

Create a file called tt.py
Write the following contents

print("你好")

Run this command in the same directory:mpremote mount .
import tt

Expected behaviour

Expected to print "你好".

Observed behaviour

PS D:\PROJECTS\Github\MicroPython-uFont> mpremote mount .
Local directory . is mounted at /remote
Connected to MicroPython at COM6
Use Ctrl-] or Ctrl-x to exit this shell
>
MicroPython v1.22.1 on 2024-01-05; Raspberry Pi Pico with RP2040
Type "help()" for more information.
>>> import tt
Traceback (most recent call last):
  File "<frozen runpy>", line 198, in _run_module_as_main
  File "<frozen runpy>", line 88, in _run_code
  File "C:\Users\YHW\AppData\Local\Programs\Python\Python312\Scripts\mpremote.exe\__main__.py", line 7, in <module>
  File "C:\Users\YHW\AppData\Local\Programs\Python\Python312\Lib\site-packages\mpremote\main.py", line 536, in main
    do_repl(state, argparse_repl().parse_args([]))
  File "C:\Users\YHW\AppData\Local\Programs\Python\Python312\Lib\site-packages\mpremote\repl.py", line 89, in do_repl
    do_repl_main_loop(
  File "C:\Users\YHW\AppData\Local\Programs\Python\Python312\Lib\site-packages\mpremote\repl.py", line 54, in do_repl_main_loop  
    console_out_write(console_data_out)
  File "C:\Users\YHW\AppData\Local\Programs\Python\Python312\Lib\site-packages\mpremote\repl.py", line 83, in console_out_write  
    console.write(b)
  File "C:\Users\YHW\AppData\Local\Programs\Python\Python312\Lib\site-packages\mpremote\console.py", line 119, in write
    buf = buf.decode() if isinstance(buf, bytes) else buf
          ^^^^^^^^^^^^
UnicodeDecodeError: 'utf-8' codec can't decode bytes in position 0-1: unexpected end of data

Additional Information

Obviously this error occurs on the PC, so I guess there must be something wrong with the mpremote source code. The error is also triggered when printing other unicode characters, such as Japanese, emoji, etc.

As far as I know, many people use mpremote mount . to quickly demo their code, and I'd like to, but something went wrong.

Is there any way to avoid this problem?
I could convert unicode characters to hexadecimal and print them, but that's pointless.
Printing unicode characters works perfectly fine with tools like thonny.

Code of Conduct

Yes, I agree