Common errors

Read a traceback from the bottom: the last line names the error, the lines above show the file and line where it happened.

• NameError: name 'x' is not defined — a typo, or the variable is used before it is assigned.
• IndentationError / TabError — the lines of one block are not indented the same; use 4 spaces everywhere.
• TypeError: can only concatenate str (not "int") to str — convert first: "Age: " + str(age), or use an f-string.
• IndexError: list index out of range — the index is ≥ len(list); remember indexes start at 0.
• KeyError: 'name' — the dict has no such key; use d.get("name") or check "name" in d.
• ValueError: invalid literal for int() — the text is not a whole number (int("3.5"), int("")).
• EOFError: EOF when reading a line — input() found no more input; fill in the Input tab.
• ModuleNotFoundError — a third-party package, or a file name that does not match the import.

values = ["10", "x", "7"]
total = 0
for v in values:
    try:
        total += int(v)
    except ValueError:
        print(f"skipped {v!r}")
print("total:", total)

skipped 'x'
total: 17