Comfy-Org/ComfyUI · error · ValueError

Unsupported text format: {format!r}

Error message

Unsupported text format: {format!r}

What it means

The SaveText-style node maps a format combo value to a file extension via a FORMAT_EXTENSIONS dict. If the format value is not a key in that dict (extension lookup returns None), the node refuses to save. In practice this happens when the workflow JSON carries a stale or hand-edited format value not present in the node's current combo options.

Source

Thrown at comfy_extras/nodes_text.py:39

            node_id="SaveText",
            search_aliases=["save text", "write text", "export text"],
            display_name="Save Text",
            category="text",
            description="Save text content to a file in the output directory.",
            inputs=[
                io.String.Input("text", force_input=True),
                io.String.Input("filename_prefix", default="ComfyUI"),
                io.Combo.Input("format", options=list(cls.FORMAT_EXTENSIONS), default="txt"),
            ],
            outputs=[io.String.Output(display_name="text")],
            is_output_node=True,
        )

    @classmethod
    def execute(cls, text, filename_prefix, format):
        extension = cls.FORMAT_EXTENSIONS.get(format)
        if extension is None:
            raise ValueError(f"Unsupported text format: {format!r}")

        full_output_folder, filename, counter, subfolder, filename_prefix = folder_paths.get_save_image_path(
            filename_prefix,
            folder_paths.get_output_directory(),
            1,
            1,
        )

        file = f"{filename}_{counter:05}.{extension}"
        filepath = os.path.join(full_output_folder, file)

        if extension == "json":
            # tries to pretty print otherwise saves normally
            try:
                data = json.loads(text)
                with open(filepath, "w", encoding="utf-8") as f:
                    json.dump(data, f, indent=2, ensure_ascii=False)
            except json.JSONDecodeError:

View on GitHub (pinned to 1c6d8d45b3)

Solutions

1. Re-select the format in the node UI so the widget value matches a current option (e.g. txt, json)
2. If submitting via API, set format to one of the keys exposed by the node's define_schema combo options
3. Remove stale widget values from the workflow JSON

Example fix

# API prompt: use a listed option
# before
"format": "markdown"
# after
"format": "txt"

valid = set(SaveText.FORMAT_EXTENSIONS)  # from the node class
if format not in valid:
    format = "txt"

def is_supported_text_format(fmt: str, node_cls) -> bool:
    return fmt in node_cls.FORMAT_EXTENSIONS

When it happens

Trigger: Executing a workflow where the format widget value was serialized as something not in FORMAT_EXTENSIONS — e.g. an old value from a previous node version, a hand-edited workflow file, or a client sending an arbitrary combo string that bypasses UI validation.

Common situations: Loading old workflows after the node's supported format list changed; API-driven prompt submissions with an unvalidated combo string; copied nodes between graphs carrying a removed format option.

Related errors

• Unsupported audio format: {format!r}

AI-assisted analysis of Comfy-Org/ComfyUI@1c6d8d45b3 (2026-08-14). Data as JSON: /api/errors/22295bd02a228afb. Report an issue: GitHub.