plandex-ai/plandex · error

Error marshalling response: %v

Error message

Error marshalling response: %v

What it means

GetFileMapHandler builds a shared.GetFileMapResponse from the file map bodies produced by the project map job queue and serializes it with encoding/json. This error is returned when json.Marshal fails on that response struct, which is extremely rare for JSON-tagged plain structs and normally indicates an unsupported value reached the payload.

Source

Thrown at app/server/handlers/file_maps.go:95

		return
	}

	select {
	case <-r.Context().Done():
		http.Error(w, "Request was cancelled", http.StatusRequestTimeout)
		return
	case maps := <-results:
		if maps == nil {
			http.Error(w, "Mapping timed out", http.StatusRequestTimeout)
			return
		}

		resp := shared.GetFileMapResponse{
			MapBodies: maps,
		}
		respBytes, err := json.Marshal(resp)
		if err != nil {
			http.Error(w, fmt.Sprintf("Error marshalling response: %v", err), http.StatusInternalServerError)
			return
		}
		w.Header().Set("Content-Type", "application/json")
		w.Write(respBytes)

		log.Printf("GetFileMapHandler success - writing response bytes: %d", len(respBytes))
	}
}

func LoadCachedFileMapHandler(w http.ResponseWriter, r *http.Request) {
	log.Println("Received request for LoadCachedFileMapHandler")

	auth := Authenticate(w, r, true)
	if auth == nil {
		return
	}

	vars := mux.Vars(r)

View on GitHub (pinned to e2d772072e)

Solutions

1. Check the %v detail in the response/log — 'json: unsupported type: X' pinpoints the exact field type causing the failure
2. Run 'go get github.com/plandex-ai/plandex-shared@latest' (or the matching version) so server and shared types are in sync, then rebuild
3. If a custom type inside the response defines MarshalJSON, fix or wrap it so it cannot fail, or make its output JSON-safe
4. As a robustness fix, log respBytes marshalling errors server-side and return a structured API error rather than a bare 500 string

Example fix

// before
respBytes, err := json.Marshal(resp)
if err != nil {
    http.Error(w, fmt.Sprintf("Error marshalling response: %v", err), http.StatusInternalServerError)
    return
}
// after
respBytes, err := json.Marshal(resp)
if err != nil {
    log.Printf("GetFileMapHandler: marshal error: %v", err)
    writeApiError(w, shared.ApiError{Type: shared.ApiErrorTypeOther, Status: http.StatusInternalServerError, Msg: "Error marshalling response"})
    return
}

// Go client: pre-serialize the equivalent payload to detect unsupported types before the call
type getReq struct{ MapInputs map[string]string }
if _, err := json.Marshal(getReq{MapInputs: inputs}); err != nil {
    return fmt.Errorf("refusing to call GetFileMap: %w", err)
}

func isMarshalable(v any) bool {
    _, err := json.Marshal(v)
    return err == nil
}

resp, err := client.GetFileMap(ctx, inputs)
if err != nil {
    if strings.Contains(err.Error(), "Error marshalling response") {
        // 500 from server-side json.Marshal — log server details, upgrade shared types
        return fmt.Errorf("file map response not serializable: %w", err)
    }
    return err
}

When it happens

Trigger: The marshalled GetFileMapResponse contains a value json.Marshal cannot encode — e.g. a field of an unsupported type (channel, func, complex number), a self-referential structure causing 'json: unsupported type', or a custom MarshalJSON method returning an error inside FileMapBodies.

Common situations: A shared package upgrade changed FileMapBodies/MapBodies to include a field with a non-serializable type or bad MarshalJSON; version mismatch between plandex-server and plandex-shared modules; a map job produced corrupt/typed-nil data that a custom marshaller chokes on.

Understand the failure class

Background: "JSON serialization failed", "not JSON serializable", "Failed to serialize": why JSON marshaling errors happen and how to fix them — this error's family across 46 libraries.

Related errors

• Error marshalling response
• Error marshalling response
• error marshalling models: %v
• error marshalling model pack: %v
• error marshalling current plan settings: %v

AI-assisted analysis of plandex-ai/plandex@e2d772072e (2026-09-05). Data as JSON: /api/errors/eab57135a84fa637. Report an issue: GitHub.