hashicorp/packer · error

No '=' value in arg: %s

Error message

No '=' value in arg: %s

What it means

CLI flag parsing error from the -var key=value flag parser: the argument contains no '=' separator, so it cannot be split into a variable name and value. Detected via strings.Index(raw, "=") returning -1.

Source

Thrown at command/flag-kv/flag.go:22

package kvflag

import (
	"fmt"
	"strings"
)

// Flag is a flag.Value implementation for parsing user variables
// from the command-line in the format of '-var key=value'.
type Flag map[string]string

func (v *Flag) String() string {
	return ""
}

func (v *Flag) Set(raw string) error {
	idx := strings.Index(raw, "=")
	if idx == -1 {
		return fmt.Errorf("No '=' value in arg: %s", raw)
	}

	if *v == nil {
		*v = make(map[string]string)
	}

	key, value := raw[0:idx], raw[idx+1:]
	(*v)[key] = value
	return nil
}

View on GitHub (pinned to eb36e3c3e4)

Solutions

1. Rewrite the argument as -var key=value with an equals sign
2. Quote the whole flag if the value contains spaces: -var "key=some value"

When it happens

Trigger: Thrown at command/flag-kv/flag.go:22 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of hashicorp/packer@eb36e3c3e4 (2026-09-05). Data as JSON: /api/errors/bea0d1cd45a83bf2. Report an issue: GitHub.