Linemode must be between 1 and 20 characters long

Error message

Linemode must be between 1 and 20 characters long

What it means

The `linemode` action deserializes into its form, then validates that the new linemode string is 1–20 characters long; empty or longer strings bail with this message. It guards against nonsensical or oversized linemode labels being applied to the manager UI.

Source

Thrown at yazi-parser/src/mgr/linemode.rs:19

use anyhow::bail;
use mlua::{ExternalError, FromLua, IntoLua, Lua, Value};
use serde::Deserialize;
use yazi_shared::event::ActionCow;

#[derive(Debug, Deserialize)]
pub struct LinemodeForm {
	#[serde(alias = "0")]
	pub new: String,
}

impl TryFrom<ActionCow> for LinemodeForm {
	type Error = anyhow::Error;

	fn try_from(a: ActionCow) -> Result<Self, Self::Error> {
		let me: Self = a.deserialize()?;

		if me.new.is_empty() || me.new.len() > 20 {
			bail!("Linemode must be between 1 and 20 characters long");
		}

		Ok(me)
	}
}

impl FromLua for LinemodeForm {
	fn from_lua(_: Value, _: &Lua) -> mlua::Result<Self> { Err("unsupported".into_lua_err()) }
}

impl IntoLua for LinemodeForm {
	fn into_lua(self, _: &Lua) -> mlua::Result<Value> { Err("unsupported".into_lua_err()) }
}

View on GitHub (pinned to 5f901b886b)

Solutions

Pass a linemode name between 1 and 20 bytes.
Trim or truncate the custom linemode label before emitting the action.
If using a multibyte label, keep total byte length ≤ 20 (e.g. slice on char boundaries).

Example fix

-- before (Lua)
ya.manager_emit("linemode", { mode }) -- mode may be ""
-- after
if mode ~= nil and #mode > 0 and #mode <= 20 then
  ya.manager_emit("linemode", { mode })
end

Defensive patterns

Strategy: validation

Validate before calling

assert!(!new.is_empty() && new.len() <= 20, "linemode name must be 1..=20 bytes");

Type guard

fn is_valid_linemode(s: &str) -> bool {
    !s.is_empty() && s.len() <= 20
}

Try / catch

match LinemodeForm::try_from(action) {
    Ok(form) => apply(form),
    Err(e) if e.to_string().contains("Linemode must be between") => {
        eprintln!("linemode name out of range: {e}")
    }
    Err(e) => return Err(e),
}

Prevention

Truncate or trim custom linemode names to ≤20 bytes before emitting.
Remember the limit is bytes, not chars — multibyte labels count more.
Handle empty lookups (mode == nil/"") by skipping the emit.

When it happens

Trigger: Calling the `mgr:linemode` action with `new` = "" or a string longer than 20 characters (length measured in bytes via `str::len`).

Common situations: Keymap/config or Lua plugin passing an empty linemode after a failed lookup; long custom linemode names exceeding 20 bytes; multi-byte UTF-8 names where byte length exceeds 20 despite few characters.

Related errors

AI-assisted analysis of sxyazi/yazi@5f901b886b (2026-09-02). Data as JSON: /api/errors/fe1ac9365cc31de3. Report an issue: GitHub.