TypeError: 'NoneType' object is not iterable — how to fix

Traceback (most recent call last):
  File "app.py", line 9, in <module>
    for item in get_items():
TypeError: 'NoneType' object is not iterable

Quick fix: Find which value is None (print it right before the line). Make sure the function returns a list on every path (return [] instead of falling off the end), don't assign the result of in-place methods (items.sort() returns None; use sorted(items)), and guard optional values: for x in items or []:.

What it means

Something tried to iterate over None: a for loop, tuple unpacking (a, b = value), list(), sorted(), sum(), in, *args expansion or ", ".join(...). Since Python 3.10 unpacking gives a slightly different message: TypeError: cannot unpack non-iterable NoneType object. Same causes, same fixes.

Find the culprit first:

result = get_items()
print(type(result), result)

Cause 1: the function has no return on some path

A function that ends without return returns None:

def get_items(user):
    if user.active:
        return user.items
    # inactive users fall off the end -> None

for item in get_items(user):   # TypeError
    ...

Fix: return an empty collection on every path.

def get_items(user):
    if user.active:
        return user.items
    return []

The same happens when you print() a value instead of returning it.

Cause 2: assigning the result of an in-place method

list.sort(), list.append(), list.extend(), list.reverse(), dict.update(), random.shuffle() modify the object and return None:

items = items.sort()      # items is now None
for x in items: ...       # TypeError

Fix:

items.sort()              # in place, don't reassign
# or
items = sorted(items)     # returns a new list

Cause 3: unpacking a function that returns None

def load():
    try:
        return read_a(), read_b()
    except OSError as e:
        log(e)            # returns None here

a, b = load()             # cannot unpack non-iterable NoneType object

Re-raise the exception, or return a default tuple such as return None, None, and handle it at the call site.

Cause 4: an API, regex or lookup returned None

Many functions return None on "not found":

m = re.match(r"(\d+)-(\d+)", text)
start, end = m.groups() if m else (None, None)

data = response.json().get("items")   # None if the key is missing
for item in data or []:
    ...

dict.get(key) returns None unless you pass a default: d.get("items", []). Test your patterns with the regex tester if a re.match unexpectedly returns None.

Cause 5: optional arguments defaulting to None

def process(values=None):
    for v in values:      # TypeError when called as process()
        ...

Fix:

def process(values=None):
    if values is None:
        values = []
    for v in values:
        ...

Don't use values=[] as the default — mutable defaults are shared between calls.

Cause 6: pandas / ORM methods with inplace=True

df = df.dropna(inplace=True) sets df to None. Either use inplace=True without assignment, or drop inplace and assign: df = df.dropna().

Last updated 2026-11-05.