Morganamilo/paru · error

value can not be empty for key

Error message

value can not be empty for key '{}'

What it means

In this crate's pacman.conf INI parser (src/config.rs:941), parse_directive requires a value for every key it processes. When a directive such as `Include` appears with no value after the `=`, the parser bails with "value can not be empty for key '{}'". This is a strict config-validation error: the parser refuses to guess defaults for directives that need an operand (e.g. an Include path pointing at another config fragment).

Solutions

  1. Open the pacman.conf (and every file it Includes) and give the offending key a value: `Include = /etc/pacman.d/mirrorlist`.
  2. If the directive is unused, delete the entire line or comment it out with `#` instead of leaving an empty value.
  3. Regenerate a known-good pacman.conf (e.g. `pacman-conf` output or distro default /etc/pacman.conf) and re-apply customizations.
  4. Validate the config before use with `pacman-conf` or the crate's parser on a copy so failures are caught early.

Example fix

// before (pacman.conf)
Include =

// after (pacman.conf)
Include = /etc/pacman.d/mirrorlist
Defensive patterns

Strategy: validation

Validate before calling

// Pre-validate pacman.conf lines before handing to the parser
fn validate_no_empty_values(path: &str) -> Result<(), String> {
    for (n, line) in std::fs::read_to_string(path)?.lines().enumerate() {
        let line = line.trim();
        if line.is_empty() || line.starts_with('#') || line.starts_with('[') { continue; }
        match line.split_once('=') {
            Some((k, v)) if v.trim().is_empty() => {
                return Err(format!("line {}: empty value for key '{}'", n + 1, k.trim()))
            }
            None => return Err(format!("line {}: not key=value: '{}'", n + 1, line)),
            _ => {}
        }
    }
    Ok(())
}

Prevention

When it happens

Trigger: Calling pacmanconf::Config::expand_with_opts / parse on a pacman.conf (or any file it Includes) that contains a directive with an empty or missing value — e.g. a line reading just `Include` or `Include =` with nothing after the `=`. ParseArg in src/args.rs and chroot setup in src/chroot.rs:29 both funnel through this parser.

Common situations: Hand-edited pacman.conf where the value was accidentally deleted; a generated pacstrap/chroot pacman.conf template with a placeholder never filled in; a blank `Include =` line left behind after commenting out a repo; copy-paste truncation of the config line.

Understand the failure class

Background: "must not be empty", "cannot be empty" — required-field validation errors across open-source libraries — this error's family across 41 libraries.

Related errors

AI-assisted analysis of Morganamilo/paru@9ac3578807 (2026-09-12). Data as JSON: /api/errors/c21097aea63c320f. Report an issue: GitHub.

Appendix: source

Thrown at src/config.rs:941

            return !(args.has_arg("p", "print")
                || args.has_arg("p", "print-format")
                || args.has_arg("s", "search")
                || args.has_arg("l", "list")
                || args.has_arg("g", "groups")
                || args.has_arg("i", "info")
                || (args.has_arg("c", "clean") && !self.mode.repo()));
        } else if self.op == Op::Upgrade || self.op == Op::Build {
            return true;
        }

        false
    }

    fn parse_directive(&mut self, key: &str, value: Option<&str>) -> Result<()> {
        if key == "Include" {
            let value = match value {
                Some(value) => value,
                None => bail!(tr!("value can not be empty for key '{}'", key)),
            };

            let ini = std::fs::read_to_string(value)?;

            let section = self.section.clone();
            let section = section.as_deref();
            let section = self
                .parse_with_section(section, Some(value), &ini)?
                .map(|s| s.to_string());
            self.section = section;
            return Ok(());
        }

        let section = match &self.section {
            Some(section) => section.as_str(),
            None => bail!(tr!("key '{}' does not belong to a section", key)),
        };

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