caddyserver/caddy · error

unsupported matcher data type: %s

Error message

unsupported matcher data type: %s

What it means

Error "unsupported matcher data type: %s" thrown in caddyserver/caddy.

Source

Thrown at modules/caddyhttp/celmatcher.go:405

// The existing CELMatcherImpl support methods are configured to support a
// limited set of function signatures. For strong type validation you may need
// to provide a custom macro which does a more detailed analysis of the CEL
// literal provided to the macro as an argument.
func CELMatcherImpl(macroName, funcName string, matcherDataTypes []*cel.Type, fac any) (cel.Library, error) {
	requestType := cel.ObjectType("http.Request")
	var macro parser.Macro
	switch len(matcherDataTypes) {
	case 1:
		matcherDataType := matcherDataTypes[0]
		switch matcherDataType.String() {
		case "list(string)":
			macro = parser.NewGlobalVarArgMacro(macroName, celMatcherStringListMacroExpander(funcName))
		case cel.StringType.String():
			macro = parser.NewGlobalMacro(macroName, 1, celMatcherStringMacroExpander(funcName))
		case CELTypeJSON.String():
			macro = parser.NewGlobalMacro(macroName, 1, celMatcherJSONMacroExpander(funcName))
		default:
			return nil, fmt.Errorf("unsupported matcher data type: %s", matcherDataType)
		}
	case 2:
		if matcherDataTypes[0] == cel.StringType && matcherDataTypes[1] == cel.StringType {
			macro = parser.NewGlobalMacro(macroName, 2, celMatcherStringListMacroExpander(funcName))
			matcherDataTypes = []*cel.Type{cel.ListType(cel.StringType)}
		} else {
			return nil, fmt.Errorf("unsupported matcher data type: %s, %s", matcherDataTypes[0], matcherDataTypes[1])
		}
	case 3:
		// nolint:gosec // false positive, impossible to be out of bounds; see: https://github.com/securego/gosec/issues/1525
		if matcherDataTypes[0] == cel.StringType && matcherDataTypes[1] == cel.StringType && matcherDataTypes[2] == cel.StringType {
			macro = parser.NewGlobalMacro(macroName, 3, celMatcherStringListMacroExpander(funcName))
			matcherDataTypes = []*cel.Type{cel.ListType(cel.StringType)}
		} else {
			// nolint:gosec // false positive, impossible to be out of bounds; see: https://github.com/securego/gosec/issues/1525
			return nil, fmt.Errorf("unsupported matcher data type: %s, %s, %s", matcherDataTypes[0], matcherDataTypes[1], matcherDataTypes[2])
		}
	}

View on GitHub (pinned to 50e54ee279)

Solutions

1. Use a supported matcher input type for the CEL matcher; check the Caddy CEL matcher documentation for supported data types.

When it happens

Trigger: Thrown at modules/caddyhttp/celmatcher.go:405 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of caddyserver/caddy@50e54ee279 (2026-08-15). Data as JSON: /api/errors/6297f81655b94160. Report an issue: GitHub.