kovidgoyal/kitty · error · ValueError

The value {val} is not a valid choice for strip_trailing_spa

Error message

The value {val} is not a valid choice for strip_trailing_spaces

What it means

strip_trailing_spaces in kitty.conf must be one of always, never, or smart. The parser lowercases and validates against a frozenset; anything else aborts option parsing with this ValueError.

Source

Thrown at kitty/options/parse.py:1359

    def shell_integration(self, val: str, ans: dict[str, typing.Any]) -> None:
        ans['shell_integration'] = shell_integration(val)

    def show_hyperlink_targets(self, val: str, ans: dict[str, typing.Any]) -> None:
        ans['show_hyperlink_targets'] = show_hyperlink_targets(val)

    def single_window_margin_width(self, val: str, ans: dict[str, typing.Any]) -> None:
        ans['single_window_margin_width'] = optional_edge_width(val)

    def single_window_padding_width(self, val: str, ans: dict[str, typing.Any]) -> None:
        ans['single_window_padding_width'] = optional_edge_width(val)

    def startup_session(self, val: str, ans: dict[str, typing.Any]) -> None:
        ans['startup_session'] = config_or_absolute_path(val)

    def strip_trailing_spaces(self, val: str, ans: dict[str, typing.Any]) -> None:
        val = val.lower()
        if val not in self.choices_for_strip_trailing_spaces:
            raise ValueError(f"The value {val} is not a valid choice for strip_trailing_spaces")
        ans["strip_trailing_spaces"] = val

    choices_for_strip_trailing_spaces = frozenset(('always', 'never', 'smart'))

    def symbol_map(self, val: str, ans: dict[str, typing.Any]) -> None:
        for k, v in symbol_map(val):
            ans["symbol_map"][k] = v

    def sync_to_monitor(self, val: str, ans: dict[str, typing.Any]) -> None:
        ans['sync_to_monitor'] = to_bool(val)

    def tab_activity_symbol(self, val: str, ans: dict[str, typing.Any]) -> None:
        ans['tab_activity_symbol'] = tab_activity_symbol(val)

    def tab_bar_align(self, val: str, ans: dict[str, typing.Any]) -> None:
        val = val.lower()
        if val not in self.choices_for_tab_bar_align:
            raise ValueError(f"The value {val} is not a valid choice for tab_bar_align")

View on GitHub (pinned to 6d5d0c4406)

Solutions

1. Replace the value with always, never, or smart
2. Do not use yes/no/true/false for this option
3. Check the option docs if unsure which keyword your kitty version supports

Example fix

# before
strip_trailing_spaces yes
# after
strip_trailing_spaces smart

value = value.lower()
if value not in ('always','never','smart'):
    raise SystemExit(f'bad strip_trailing_spaces: {value}')

def is_strip_trailing_spaces(v: str) -> bool:
    return v.lower() in ('always','never','smart')

When it happens

Trigger: Setting `strip_trailing_spaces yes`, `strip_trailing_spaces true`, or `strip_trailing_spaces Smart ` (typo) in kitty.conf. Note booleans are not accepted — only the three keywords.

Common situations: Users familiar with kitty's other boolean options (which take yes/no) assuming this one is boolean too; older kitty versions accepted only smart/never and new values confuse migrations.

Related errors

• The value {x} is not a known choice
• The value {val} is not a valid choice for progress_bar
• The value {val} is not a valid choice for scrollbar
• The value {val} is not a valid choice for tab_bar_align
• The value {val} is not a valid choice for tab_bar_style

AI-assisted analysis of kovidgoyal/kitty@6d5d0c4406 (2026-08-27). Data as JSON: /api/errors/c25f33f1c1a109ed. Report an issue: GitHub.