(TYPO) Error message value swap -> ValueError: not enough values to unpack

[HumanBot000]

Bug report

Bug description:

for a,b in string:

This raised issue is ValueError: not enough values to unpack (expected 2, got 1)
But it should be

ValueError: not enough values to unpack (expected 1, got 2)

because two values should be unpacked, whilst string expects only one

CPython versions tested on:

3.10

Operating systems tested on:

Windows

[Eclips4]

Hello!
I can't reproduce this behavior on Python 3.9-3.14. Can you please provide the full code?

[HumanBot000]

Hello! I can't reproduce this behavior on Python 3.9-3.14. Can you please provide the full code?

    for a, b in "foo":
        # Nothing in here
        pass

Results in

ValueError: not enough values to unpack (expected 2, got 1)

Exact Python version is 3.10.10

[JelleZijlstra]

The error message is correct. The for loop iterates over the string, so on each iteration we do something like a, b = c, where c is a single-character string (from iterating over the string). That means we expect an iterable with 2 members (for a and b), but we get one with one member (the character), as the error message says.

[Eclips4]

Oh, I misunderstood you. Yes, as @JelleZijlstra said, there's no bug. We expect two elements (a, b), but after the first iteration, we have only one element, which is incorrect.

[terryjreedy]

As Jelle said, there is only 1 value in each iteration. The first iteration tries to execute a,b = 'f'.