go-delve/delve · error

Backtick not supported in

Error message

Backtick not supported in '%s'

What it means

parseNewArgv parses the argument string for the `restart` command's new argv. It delegates tokenizing to the argv library, supplying a backtick-substitution callback that unconditionally fails: Delve's restart argv does not support backtick command substitution, so any backtick expression in the argument string produces this error naming the offending substring.

Solutions

1. Remove backticks and pass literal arguments: restart arg1 arg2.
2. Compute the value externally (in the shell) and paste the result as a plain argument.
3. Quote arguments with regular or single quotes instead of backticks.
4. Use Delve's own substitution facilities where available instead of command substitution.

Example fix

# before
restart `date +%s`
# after
restart 1725120000   # value computed in the shell, passed literally

if strings.ContainsRune(args, '`') {
    return fmt.Errorf("backtick substitution is not supported in restart arguments")
}

func hasBacktickExpr(s string) bool { return strings.ContainsRune(s, '`') }

reset, argv, redirs, err := parseNewArgv(args)
if err != nil {
    if strings.HasPrefix(err.Error(), "Backtick not supported") {
        // sanitize input: strip backticks or compute value externally
    }
    return err
}

When it happens

Trigger: Running `restart <args>` where <args> contains backtick-quoted command substitution, e.g. `restart -c `some command`` or any argument string with a ` character interpreted by the argv parser as a backtick expression.

Common situations: Users trying to embed dynamic values via shell-style command substitution in restart arguments; shell quoting habits (backticks) carried over from bash into the Delve CLI; stray backticks from copy-pasted commands.

Related errors

• command not available
• could not find target
• Frame does not exist in goroutine
• illegal commandline
• Invalid frame

AI-assisted analysis of go-delve/delve@a23773e6c3 (2026-08-31). Data as JSON: /api/errors/1864c3c6817413ef. Report an issue: GitHub.

Appendix: source

Thrown at pkg/terminal/command.go:1276

func restartIntl(t *Term, rerecord bool, restartPos string, resetArgs bool, newArgv []string, newRedirects [3]string) error {
	discarded, err := t.client.RestartFrom(rerecord, restartPos, resetArgs, newArgv, newRedirects, false)
	if err != nil {
		return err
	}
	for i := range discarded {
		fmt.Fprintf(t.stdout, "Discarded %s at %s: %v\n", formatBreakpointName(discarded[i].Breakpoint, false), t.formatBreakpointLocation(discarded[i].Breakpoint), discarded[i].Reason)
	}
	return nil
}

func parseNewArgv(args string) (resetArgs bool, newArgv []string, newRedirects [3]string, err error) {
	if args == "" {
		return false, nil, [3]string{}, nil
	}
	v, err := argv.Argv(args,
		func(s string) (string, error) {
			return "", fmt.Errorf("Backtick not supported in '%s'", s)
		},
		nil)
	if err != nil {
		return false, nil, [3]string{}, err
	}
	if len(v) != 1 {
		return false, nil, [3]string{}, fmt.Errorf("illegal commandline '%s'", args)
	}
	w := v[0]
	if len(w) == 0 {
		return false, nil, [3]string{}, nil
	}
	if w[0] == "-noargs" {
		if len(w) > 1 {
			return false, nil, [3]string{}, errors.New("too many arguments to restart")
		}
		return true, nil, [3]string{}, nil
	}

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