Start with the problem in front of you.

After execution, identify which nodes produced results and where those results reside. Node IDs, prompt IDs and filenames are different identifiers.

A rejected request needs structured error inspection. HTTP 400 is not, by itself, evidence of an unstable network and should not trigger endless resubmission.

This guide concerns an instance you own or are authorized to use. ComfyUI's native HTTP API is distinct from this site's knowledge MCP and does not authorize access to third-party services.

localhost identifies the device making the request. Its meaning differs across a browser, phone, container, notebook and remote server.

Locate the failing endpoint and distinguish the backend, logs, registry and workflow-save requests.

Use an explicit task and result contract instead of assuming an application entry script is a reusable library.

The Python server may still be running while the canvas fails. Distinguish static assets, JavaScript extensions and an absent backend before reinstalling unrelated models.

Core source, Desktop shell, frontend package, templates and custom nodes are not one indivisible version. An update can leave some components behind.

Distinguish registry retrieval, search filters, installed code and Python imports.

Repeatedly starting ComfyUI can collide with an existing healthy instance. A port conflict is not permission to terminate every Python process.

A fast completion can involve cached execution, a preview-only endpoint, temporary storage or a client misreading events. It is not automatically a failed generation.

A connected socket and accepted queue request are not a result. Check client_id, prompt_id, terminal events and history together.

Preserve an export before investigating draft storage, file downloads or API-format confusion.