Python 3.11+tomllibexception

tomllib.TOMLDecodeError

exceptions

The exception tomllib raises for invalid TOML; a subclass of ValueError whose message names the line and column.

Syntax

except tomllib.TOMLDecodeError as e: ...

Because it is a ValueError, a generic except ValueError catches it too. The lineno, colno, pos and msg attributes exist only from Python 3.14; older versions report the location only in the message text. A common cause is an unquoted string: name = Alice is an error, not a string.

Examples

import tomllib
try:
    tomllib.loads('name = Alice')
except tomllib.TOMLDecodeError as e:
    print(e)  # → Invalid value (at line 1, column 8)
    print(isinstance(e, ValueError))  # → True

# Python 3.14+
import tomllib
try:
    tomllib.loads('a = 1\nb = ')
except tomllib.TOMLDecodeError as e:
    print(e.lineno, e.colno)  # → 2 5

See also

Common errors

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