Bug report

Bug description:

Environment

• Python: 3.14.4
• OS: Windows 11 25H2
• Launch method: py
• Terminal: PowerShell and Command Prompt (reproduced in both)

Description

The REPL raises an unhandled UnicodeEncodeError before executing the pasted code.

The traceback ends with:

UnicodeEncodeError: 'utf-8' codec can't encode characters in position 7-8: surrogates not allowed

The traceback originates from _pyrepl:

Lib\_pyrepl\readline.py
Lib\_pyrepl\reader.py
Lib\_pyrepl\utils.py
Lib\tokenize.py

Steps to reproduce

1. Start the REPL:

py

2. Paste the following code as a single multiline paste:

print("😢")
print("💫")
print("✨")

3. The REPL crashes with UnicodeEncodeError.

Expected behavior

The pasted code should execute normally and print the emoji.

Actual behavior

The REPL crashes before execution with a UnicodeEncodeError originating from _pyrepl.

Additional observations

• Running the exact same code from a .py file works correctly.
• A single-line input such as:

print("✨")

works correctly.

• The problem only occurs when pasting multiline code.
• The issue reproduces when copying from Windows Notepad, so it does not appear to be specific to ChatGPT or a browser.
• The issue reproduces in both PowerShell and Command Prompt.
• The issue reproduces every time on my system.

Full traceback

Traceback (most recent call last):
File "C:\Users\tetuw\AppData\Local\Python\pythoncore-3.14-64\Lib_pyrepl\readline.py", line 395, in multiline_input
return reader.readline()
~~~~~~~~~~~~~~~^^
File "C:\Users\tetuw\AppData\Local\Python\pythoncore-3.14-64\Lib_pyrepl\reader.py", line 758, in readline
self.handle1()
~~~~~~~~~~~~^^
File "C:\Users\tetuw\AppData\Local\Python\pythoncore-3.14-64\Lib_pyrepl\reader.py", line 741, in handle1
self.do_cmd(cmd)
~~~~~~~~~~~^^^^^
File "C:\Users\tetuw\AppData\Local\Python\pythoncore-3.14-64\Lib_pyrepl\reader.py", line 671, in do_cmd
self.refresh()
~~~~~~~~~~~~^^
File "C:\Users\tetuw\AppData\Local\Python\pythoncore-3.14-64\Lib_pyrepl\reader.py", line 648, in refresh
self.screen = self.calc_screen()
~~~~~~~~~~~~~~~~^^
File "C:\Users\tetuw\AppData\Local\Python\pythoncore-3.14-64\Lib_pyrepl\completing_reader.py", line 261, in calc_screen
screen = super().calc_screen()
File "C:\Users\tetuw\AppData\Local\Python\pythoncore-3.14-64\Lib_pyrepl\reader.py", line 315, in calc_screen
colors = list(gen_colors(self.get_unicode()))
File "C:\Users\tetuw\AppData\Local\Python\pythoncore-3.14-64\Lib_pyrepl\utils.py", line 115, in gen_colors
for color in gen_colors_from_token_stream(gen, line_lengths):
~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^
File "C:\Users\tetuw\AppData\Local\Python\pythoncore-3.14-64\Lib_pyrepl\utils.py", line 175, in gen_colors_from_token_stream
for prev_token, token, next_token in token_window:
^^^^^^^^^^^^
File "C:\Users\tetuw\AppData\Local\Python\pythoncore-3.14-64\Lib_pyrepl\utils.py", line 382, in prev_next_window
window = deque((None, next(iterator)), maxlen=3)
~~~~^^^^^^^^^^
File "C:\Users\tetuw\AppData\Local\Python\pythoncore-3.14-64\Lib\tokenize.py", line 588, in _generate_tokens_from_c_tokenizer
for info in it:
^^
UnicodeEncodeError: 'utf-8' codec can't encode characters in position 7-8: surrogates not allowed

CPython versions tested on:

3.14

Operating systems tested on:

Windows