Trojan settings: "servers" should have one and only one memb

Error message

Trojan settings: "servers" should have one and only one member. Multiple endpoints in "servers" should use multiple Trojan outbounds and routing balancer instead

What it means

Thrown when building a Trojan client config: after the legacy single-server fields are normalized into c.Servers, the list must contain exactly one entry. Multiple servers in one outbound are rejected by design — each endpoint needs its own Trojan outbound plus a routing balancer.

Source

Thrown at infra/conf/trojan.go:58

// Build implements Buildable
func (c *TrojanClientConfig) Build() (proto.Message, error) {
	errors.PrintNonRemovalDeprecatedFeatureWarning("Trojan (with no Flow, etc.)", "VLESS with Flow & Seed")

	if c.Address != nil {
		c.Servers = []*TrojanServerTarget{
			{
				Address:  c.Address,
				Port:     c.Port,
				Level:    c.Level,
				Email:    c.Email,
				Password: c.Password,
				Flow:     c.Flow,
			},
		}
	}
	if len(c.Servers) != 1 {
		return nil, errors.New(`Trojan settings: "servers" should have one and only one member. Multiple endpoints in "servers" should use multiple Trojan outbounds and routing balancer instead`)
	}

	config := &trojan.ClientConfig{}

	for _, rec := range c.Servers {
		if rec.Address == nil {
			return nil, errors.New("Trojan server address is not set.")
		}
		if rec.Port == 0 {
			return nil, errors.New("Invalid Trojan port.")
		}
		if rec.Password == "" {
			return nil, errors.New("Trojan password is not specified.")
		}
		if rec.Flow != "" {
			return nil, errors.PrintRemovedFeatureError(`Flow for Trojan`, ``)
		}

View on GitHub (pinned to 7d214f8b09)

Solutions

Keep exactly one server object in the Trojan outbound's "servers"
For multiple endpoints, create one Trojan outbound per server and distribute traffic with a routing "balancer" section
Point a load-balancer/health-check layer in front and expose a single address to Xray

Example fix

// before
"servers": [ {"address":"a.example","port":443,...}, {"address":"b.example","port":443,...} ]
// after
// outbound[0]: trojan -> a.example ; outbound[1]: trojan -> b.example ; routing.balancer tags both

Defensive patterns

Strategy: validation

Validate before calling

servers := gjson.Get(config, "outbounds.#(protocol=trojan).settings.servers").Array()
if len(servers) != 1 {
    return errors.New("trojan outbound must have exactly one server; use multiple outbounds + balancer")
}

Prevention

Model 'one outbound per endpoint' in config templates from the start
Use routing balancers for multi-endpoint Trojan, never a multi-element servers array

When it happens

Trigger: Writing "settings": { "servers": [ {...}, {...} ] } with two or more server objects in a Trojan outbound; or an empty servers array.

Common situations: Migrating a client config that lists several Trojan nodes for 'failover' in one outbound — the Trojan client protocol connects to a single endpoint, so this pattern is not supported.

Related errors

AI-assisted analysis of XTLS/Xray-core@7d214f8b09 (2026-08-15). Data as JSON: /api/errors/0fa4c10839e9f822. Report an issue: GitHub.