What causes "logger handler is not enabled" in owasp-amass/amass?

Raise the handler's minimum level (e.g. slog.SetLogLoggerLevel or handler level option) so the message's level is enabled.

owasp-amass/amass · warning

logger handler is not enabled

Error message

logger handler is not enabled

What it means

WriteLogMessage checks l.Handler().Enabled(ctx, record.Level) before dispatching a slog record. If the handler reports the level as not enabled, the message is not delivered and this error is returned instead of silently dropping the log line.

Solutions

Raise the handler's minimum level (e.g. slog.SetLogLoggerLevel or handler level option) so the message's level is enabled.
Verify the logger returned by NewFileLogger is actually installed (not a discarded handler).
Ignore the error if dropping low-level messages is intended; treat it as a signal, not a fault.

Example fix

// before
logger := slog.New(slog.NewTextHandler(io.Discard, &slog.HandlerOptions{Level: slog.LevelError}))
tools.WriteLogMessage(logger, slog.LevelDebug, "msg") // error
// after
logger := slog.New(slog.NewTextHandler(w, &slog.HandlerOptions{Level: slog.LevelDebug}))
tools.WriteLogMessage(logger, slog.LevelDebug, "msg")

Defensive patterns

Strategy: try-catch

Validate before calling

ctx := context.Background()
if !logger.Handler().Enabled(ctx, level) {
    // skip or raise handler level first
}

Try / catch

if err := tools.WriteLogMessage(logger, level, msg); err != nil {
    if err.Error() == "logger handler is not enabled" {
        // drop or buffer the message; optionally log to stderr
    }
}

Prevention

Align the handler's minimum level with every level the code emits.
Don't install discard handlers in paths that must log.
Test logging setup at application startup with one message per level.

When it happens

Trigger: Calling WriteLogMessage with a logger whose handler has the record's level filtered out (e.g. handler configured at LevelError while writing a Debug/Info message), or with a discarded/no-op handler.

Common situations: Application verbosity configured below the level used by callers (production builds with LevelWarn); using slog.DiscardHandler or a custom handler whose Enabled() returns false; writing debug logs in release binaries.

Related errors

AI-assisted analysis of owasp-amass/amass@79299dce87 (2026-09-06). Data as JSON: /api/errors/6aa780b77e13fcab. Report an issue: GitHub.

Appendix: source

Thrown at internal/tools/log.go:33

	"strings"

	afmt "github.com/owasp-amass/amass/v5/internal/afmt"
	slogcommon "github.com/samber/slog-common"
	slogsyslog "github.com/samber/slog-syslog/v2"
)

func WriteLogMessage(l *slog.Logger, message string) error {
	record, err := afmt.JSONLogToRecord(message)
	if err != nil {
		return err
	}

	ctx := context.Background()
	if l.Handler().Enabled(ctx, record.Level) {
		return l.Handler().Handle(ctx, record)
	}

	return errors.New("logger handler is not enabled")
}

func NewFileLogger(dir, logfile string) (*slog.Logger, error) {
	if logfile == "" {
		return nil, fmt.Errorf("no log file specified")
	}

	if dir != "" {
		if err := os.MkdirAll(dir, 0640); err != nil {
			return nil, fmt.Errorf("failed to create the log directory: %v", err)
		}
	}

	f, err := os.OpenFile(filepath.Join(dir, logfile), os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
	if err != nil {
		return nil, fmt.Errorf("failed to open the log file: %v", err)
	}

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