Package version '#{@version}' includes dashes, converting to

Error message

Package version '#{@version}' includes dashes, converting to underscores

What it means

RPM's Version field must not contain dashes; rpmbuild rejects them. When the rpm output target sees a String version containing '-', it rewrites every dash to an underscore in place and logs this warning. The package still builds, but its version metadata differs from the string you passed.

Source

Thrown at lib/fpm/package/rpm.rb:640

    end
  end # def prefix

  def build_sub_dir
    return "BUILD"
    #return File.join("BUILD", prefix)
  end # def build_sub_dir

  def summary
    if !attributes[:rpm_summary]
      return @description.split("\n").find { |line| !line.strip.empty? } || "_"
    end

    return attributes[:rpm_summary]
  end # def summary

  def version
    if @version.kind_of?(String) and @version.include?("-")
      logger.warn("Package version '#{@version}' includes dashes, converting" \
                   " to underscores")
      @version = @version.gsub(/-/, "_")
    end

    return @version
  end

  # The default epoch value must be nil, see #381
  def epoch
    return @epoch if @epoch.is_a?(Numeric)

    if @epoch.nil? or @epoch.empty?
      return nil
    end

    return @epoch
  end # def epoch

View on GitHub (pinned to b6d77ba72a)

Solutions

Strip or replace dashes before invoking fpm: `VER=${VER//-/_}`
Split semver prereleases the RPM way: `--version 1.2.3 --iteration 0.1.beta1`
Derive the version from the tag only, e.g. `git describe --tags --abbrev=0`, not the full describe string

Example fix

# before
fpm -s dir -t rpm -n app -v $(git describe --tags) .

# after
fpm -s dir -t rpm -n app -v $(git describe --tags --abbrev=0) --iteration $(git rev-list --count HEAD) .

Defensive patterns

Strategy: validation

Validate before calling

VER="${VER//-/_}"
if [[ "$VER" == *-* ]]; then
  echo "version contains dashes after sanitize: $VER" >&2
  exit 1
fi

Type guard

def rpm_safe_version?(str)
  str.is_a?(String) && !str.include?('-') && !str.empty?
end

Prevention

Use `git describe --tags --abbrev=0` (tag only) for --version, and put the commit count into --iteration
Put semver prerelease suffixes in --iteration with underscores, per RPM convention
Assert the published rpm's %{VERSION} matches the intended tag in CI

When it happens

Trigger: Building an rpm with `--version 1.2.3-beta.1`, or with `--version $(git describe --tags)` which yields '1.2.3-14-g0abc1' that then becomes '1.2.3_14_g0abc1'.

Common situations: CI pipelines feeding git describe or npm/python prerelease versions straight into fpm; downstream tools comparing versions mismatch because the published rpm carries underscores where the tag had dashes.

Related errors

AI-assisted analysis of jordansissel/fpm@b6d77ba72a (2026-08-21). Data as JSON: /api/errors/cacf4ebedb4df133. Report an issue: GitHub.