redis/redis · error

Options -4 and -6 are mutually exclusive.

Error message

Options -4 and -6 are mutually exclusive.

What it means

redis-cli refuses to start when both the -4 (prefer IPv4) and -6 (prefer IPv6) flags are given together. The flags drive anet's address-family preference used for DNS resolution and socket connection, and they are logically contradictory, so the option parser rejects the combination and exits with status 1 at startup. It is purely an argument-validation guard emitted before any connection is attempted.

Source

Thrown at src/redis-cli.c:3153

    }

    if (!config.no_auth_warning && config.conn_info.auth != NULL) {
        fputs("Warning: Using a password with '-a' or '-u' option on the command"
              " line interface may not be safe.\n", stderr);
    }

    if (config.get_functions_rdb_mode && config.getrdb_mode) {
        fprintf(stderr,"Option --functions-rdb and --rdb are mutually exclusive.\n");
        exit(1);
    }
 
    if (config.stdin_lastarg && config.stdin_tag_arg) {
        fprintf(stderr, "Options -x and -X are mutually exclusive.\n");
        exit(1);
    }

    if (config.prefer_ipv4 && config.prefer_ipv6) {
        fprintf(stderr, "Options -4 and -6 are mutually exclusive.\n");
        exit(1);
    }

    return i;
}

static void parseEnv(void) {
    /* Set auth from env, but do not overwrite CLI arguments if passed */
    char *auth = getenv(REDIS_CLI_AUTH_ENV);
    if (auth != NULL && config.conn_info.auth == NULL) {
        config.conn_info.auth = auth;
    }

    char *cluster_yes = getenv(REDIS_CLI_CLUSTER_YES_ENV);
    if (cluster_yes != NULL && !strcmp(cluster_yes, "1")) {
        config.cluster_manager_command.flags |= CLUSTER_MANAGER_CMD_FLAG_YES;
    }
}

View on GitHub (pinned to 4f20cb4893)

Solutions

1. Pass only one of -4 or -6; omit both to let the OS/hiredis choose the default family.
2. Inspect aliases and wrappers for stale flags: run `alias redis-cli` / `type redis-cli` and grep your launcher script.
3. If the choice must be environment-specific, set it once in a config/env file rather than per-invocation.

Example fix

// before
redis-cli -4 -6 -h myhost PING
// after
redis-cli -4 -h myhost PING

# Reject mutually-exclusive -4/-6 before launching redis-cli
args=("$@")
has4=0; has6=0
for a in "${args[@]}"; do
  case "$a" in -4) has4=1;; -6) has6=1;; esac
done
if [[ $has4 -eq 1 && $has6 -eq 1 ]]; then
  echo "Error: -4 and -6 are mutually exclusive" >&2; exit 2
fi
exec redis-cli "$@"

When it happens

Trigger: Invoking redis-cli with both flags on one command line, e.g. `redis-cli -4 -6 -h myhost PING`. The guard at redis-cli.c:3152-3155 fires because config.prefer_ipv4 and config.prefer_ipv6 are both set.

Common situations: Copy-pasted flag combos merged from two runbooks; a shell alias or wrapper script that always appends `-4` colliding with an operator who adds `-6` for an IPv6-only host; dual-stack migration where both preferences were left enabled.

Related errors

• Using -X option but stdin tag not match.
• [ERR] Wrong number of arguments for specified --cluster sub
• Unknown --cluster subcommand
• Error: invalid CLUSTER NODES reply
• Invalid address format: %s

AI-assisted analysis of redis/redis@4f20cb4893 (2026-08-10). Data as JSON: /api/errors/673ac760af5c4390. Report an issue: GitHub.