ValueError: not enough values to unpack

What you see

lines = ["ada,ada@example.com", "grace"]

for line in lines:
    name, email = line.split(",")
    print(name, email)

Traceback (most recent call last):
  File "/home/me/project/main.py", line 4, in <module>
    name, email = line.split(",")
    ^^^^^^^^^^^
ValueError: not enough values to unpack (expected 2, got 1)

ada ada@example.com

What it means

name, email = … needs exactly two items on the right. The second line has no comma, so split(",") returns a list of one item, ["grace"], and there is nothing for email.

The message gives both counts: "expected 2" is the number of names on the left, "got 1" the number of items that came.

Why it happens

• A separator that is missing from some lines, as in the example.
• A blank line, often the last one of a file: "".split(",") gives [""], one item.
• A function that returns fewer values on some path, such as one value on success and two on failure.
• Short rows in a CSV file or a list of tuples.

How to fix it

Skip lines that are blank, and check the shape before unpacking:

for line in lines:
    if not line.strip():
        continue
    parts = line.split(",")
    if len(parts) != 2:
        print("skipping", repr(line))
        continue
    name, email = parts

str.partition() always returns three items, so it never fails to unpack; a missing separator gives empty strings:

name, _, email = line.partition(",")   # "grace" gives ("grace", "", "")

How each Python version words it

Run on CPython 3.9.6, 3.10.22, 3.11.17, 3.12.15, 3.13.17, 3.14.9 and 3.15.1, on October 25, 2026.

The wording is the same in every version here.