What causes "unable to unmarshal LogEventType" in cloudflare/cloudflared?

Use an exact supported event type string, e.g. 'cloudflared.metric', 'cloudflared.log'

unable to unmarshal LogEventType

Error message

unable to unmarshal LogEventType

What it means

UnmarshalJSON for LogEventType returns this when the JSON value is a string but does not match any known event type per ParseLogEventType. The string parsed fine but is not a recognized LogEventType constant.

Source

Thrown at management/events.go:127

	default:
		return ""
	}
}

func (l LogEventType) MarshalJSON() ([]byte, error) {
	return json.Marshal(l.String())
}

func (e *LogEventType) UnmarshalJSON(data []byte) error {
	var s string
	if err := json.Unmarshal(data, &s); err != nil {
		return errors.New("unable to unmarshal LogEventType string")
	}
	if event, ok := ParseLogEventType(s); ok {
		*e = event
		return nil
	}
	return errors.New("unable to unmarshal LogEventType")
}

// LogLevel corresponds to the zerolog logging levels
// "panic", "fatal", and "trace" are exempt from this list as they are rarely used and, at least
// the first two are limited to failure conditions that lead to cloudflared shutting down.
type LogLevel int8

const (
	Debug LogLevel = 0
	Info  LogLevel = 1
	Warn  LogLevel = 2
	Error LogLevel = 3
)

func ParseLogLevel(l string) (LogLevel, bool) {
	switch l {
	case "debug":
		return Debug, true

View on GitHub (pinned to 2253eeeb25)

Solutions

Use an exact supported event type string, e.g. 'cloudflared.metric', 'cloudflared.log'
Upgrade/downgrade the client so its event names match the server's supported set
Check the ParseLogEventType switch in management/events.go for the accepted values

Example fix

// before
{"event_type": "metrics"}
// after
{"event_type": "cloudflared.metric"}

Defensive patterns

Strategy: type-guard

Validate before calling

if _, ok := management.ParseLogEventType(s); !ok { /* unknown event type, skip */ }

Type guard

func isKnownEventType(s string) bool { _, ok := management.ParseLogEventType(s); return ok }

Try / catch

var e management.LogEventType
if err := json.Unmarshal(data, &e); err != nil { log.Warn().Err(err).Str("event", s).Msg("unknown LogEventType") }

Prevention

Use the exact event type constants, not ad-hoc strings
Regenerate client types when the management API changes
Add a unit test unmarshaling every supported event name

When it happens

Trigger: ParseLogEventType(s) returns ok=false for a string like 'metrics' (correct is 'cloudflared.metric'), indicating an unknown or misspelled event type string in the JSON payload.

Common situations: Clients built against an older/newer management API version using event names that changed; hand-written test payloads with typos.

Understand the failure class

Background: Invalid enum value errors: "Unknown type", "Invalid scope", "must be one of" — when a string is not on the library's allowed list — this error's family across 23 libraries.

Related errors

AI-assisted analysis of cloudflare/cloudflared@2253eeeb25 (2026-09-06). Data as JSON: /api/errors/0c4a4ab6c65e2cb4. Report an issue: GitHub.