What causes "loading wrapped encoder module: %v" in caddyserver/caddy?

Fix the nested encoder name to a registered encoder (json, console, filter, append, etc.)

loading wrapped encoder module: %v

Error message

loading wrapped encoder module: %v

What it means

JournaldEncoder.Provision returns this when ctx.LoadModule(je, "WrappedRaw") fails to load the encoder configured inside the journald encoder's 'wrap' field. LoadModule errors mean the nested module name is not a registered encoder module ID, its JSON is malformed, or the module's own Provision/Validate failed.

Source

Thrown at modules/logging/journaldencoder.go:79

	}
}

// Provision sets up the encoder.
func (je *JournaldEncoder) Provision(ctx caddy.Context) error {
	je.ctx = ctx

	if je.WrappedRaw == nil {
		je.Encoder = &JSONEncoder{}
		if p, ok := je.Encoder.(caddy.Provisioner); ok {
			if err := p.Provision(ctx); err != nil {
				return fmt.Errorf("provisioning fallback encoder module: %v", err)
			}
		}
		je.wrappedIsDefault = true
	} else {
		val, err := ctx.LoadModule(je, "WrappedRaw")
		if err != nil {
			return fmt.Errorf("loading wrapped encoder module: %v", err)
		}
		je.Encoder = val.(zapcore.Encoder)
	}

	suppressConsoleEncoderTimestamp(je.Encoder)

	return nil
}

// ConfigureDefaultFormat will set the default wrapped format to "console"
// if the writer is a terminal. If already configured, it passes through
// the writer so a deeply nested encoder can configure its own default format.
func (je *JournaldEncoder) ConfigureDefaultFormat(wo caddy.WriterOpener) error {
	if !je.wrappedIsDefault {
		if cfd, ok := je.Encoder.(caddy.ConfiguresFormatterDefault); ok {
			return cfd.ConfigureDefaultFormat(wo)
		}
		return nil

View on GitHub (pinned to 50e54ee279)

Solutions

Fix the nested encoder name to a registered encoder (json, console, filter, append, etc.)
If a plugin encoder is intended, rebuild/obtain a Caddy binary that includes that plugin
Check the wrapped error text from LoadModule for the precise module ID problem

Example fix

# before
format journald {
    format gelf # plugin not in this build
}

# after
format journald {
    format json
}

Defensive patterns

Strategy: validation

Validate before calling

known := map[string]bool{"json": true, "console": true, "filter": true, "append": true}
if !known[nestedFormat] { return fmt.Errorf("unknown encoder %q", nestedFormat) }

Try / catch

if err := ctx.LoadModule(je, "WrappedRaw"); err != nil {
    return fmt.Errorf("journald wrap: %w", err) // inspect wrapped cause for bad module ID
}

Prevention

Use encoder names from the caddy docs; verify plugin encoders exist in your build
Prefer Caddyfile syntax so the adapter catches unknown formats at adapt time

When it happens

Trigger: Config with format journald { format <name> } where <name> is not a valid caddy.logging.encoders.* module ID, or the nested module object fails its own provisioning.

Common situations: Typos in the nested format name (e.g. 'js' vs 'json', 'gelf' without the plugin installed); using an encoder provided by a plugin in a build that lacks that plugin; malformed nested JSON from API config pushes.

Related errors

AI-assisted analysis of caddyserver/caddy@50e54ee279 (2026-08-15). Data as JSON: /api/errors/ee862142ca3e9e69. Report an issue: GitHub.