Syntax Error when adding preview image node

[Jim144a]

Recently updated my Comfyui to the latest version.

The update seems to have caused a problem with the Efficient K sampler node. It works fine until I connect a preview image node I then get SyntaxError: Unexpected non-whitespace character after JSON at position 4 (line 1 column 5).

Tried uninstalling and updating the Efficiency nodes package but I am still getting the error.

17:41:18.732 [Init] === SwarmUI v0.9.4.1 Starting at 2025-01-11 17:41:18 ===
17:41:18.768 [Init] Prepping extension: SwarmUI.Builtin_ScorersExtension.ScorersExtension...
17:41:18.770 [Init] Prepping extension: SwarmUI.Builtin_ImageBatchToolExtension.ImageBatchToolExtension...
17:41:18.770 [Init] Prepping extension: SwarmUI.Builtin_GridGeneratorExtension.GridGeneratorExtension...
17:41:18.771 [Init] Prepping extension: SwarmUI.Builtin_DynamicThresholding.DynamicThresholdingExtension...
17:41:18.771 [Init] Prepping extension: SwarmUI.Builtin_ComfyUIBackend.ComfyUIBackendExtension...
17:41:18.772 [Init] Prepping extension: SwarmUI.Builtin_AutoWebUIExtension.AutoWebUIBackendExtension...
17:41:18.812 [Init] Parsing command line...
17:41:18.813 [Init] Loading settings file...
17:41:18.835 [Init] Re-saving settings file...
17:41:18.853 [Init] Applying command line settings...
17:41:18.985 [Init] Prepping options...
17:41:19.018 [Init] Current git commit marked as date 2025-01-09 00:43:01
17:41:19.089 [Init] CPU Cores: 32 | RAM: 63.91 GiB total, 56.24 GiB available, 67.91 GiB total page file, 58.91 GiB available page file
17:41:19.090 [Init] GPU 0: NVIDIA GeForce RTX 3080 Ti | Temp 27C | Util 3% GPU, 7% Memory | VRAM 12.00 GiB total, 10.95 GiB free, 870.00 MiB used
17:41:19.190 [Init] Loading models list...
17:41:19.222 [Init] Loading backends...
17:41:19.223 [Init] Loading backends from file...
17:41:19.230 [Init] Prepping API...
17:41:19.230 [Init] Initializing backend #0 - ComfyUI Self-Starting...
17:41:19.232 [Init] Prepping webserver...
17:41:19.234 [Init] Backend request handler loop ready...
17:41:19.338 [Init] Scan for web extensions...
17:41:19.397 [Init] Readying extensions for launch...
17:41:19.398 [Init] Launching server...
17:41:19.399 [Init] Starting webserver on http://localhost:7801
17:41:19.934 [Init] Swarm is up to date! You have version 0.9.4.1, and 0.9.4.0-Beta is the latest.
17:41:19.935 [Init] Program is running.
17:41:20.438 [Init] Launch web browser...
17:41:20.666 [Init] Self-Start ComfyUI-0 on port 7821 is loading...
17:41:21.359 [Info] Creating new admin session 'local' for ::1
17:41:49.929 [Init] Self-Start ComfyUI-0 on port 7821 started.
17:43:23.556 [Warning] [ComfyUI-0/STDERR] Traceback (most recent call last):
17:43:23.558 [Warning] [ComfyUI-0/STDERR] File "C:\Swarm\SwarmUI\dlbackend\comfy\python_embeded\Lib\site-packages\aiohttp\web_protocol.py", line 480, in _handle_request
17:43:23.559 [Warning] [ComfyUI-0/STDERR] resp = await request_handler(request)
17:43:23.559 [Warning] [ComfyUI-0/STDERR] ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
17:43:23.560 [Warning] [ComfyUI-0/STDERR] File "C:\Swarm\SwarmUI\dlbackend\comfy\python_embeded\Lib\site-packages\aiohttp\web_app.py", line 569, in _handle
17:43:23.560 [Warning] [ComfyUI-0/STDERR] return await handler(request)
17:43:23.561 [Warning] [ComfyUI-0/STDERR] ^^^^^^^^^^^^^^^^^^^^^^
17:43:23.561 [Warning] [ComfyUI-0/STDERR] File "C:\Swarm\SwarmUI\dlbackend\comfy\python_embeded\Lib\site-packages\aiohttp\web_middlewares.py", line 117, in impl
17:43:23.562 [Warning] [ComfyUI-0/STDERR] return await handler(request)
17:43:23.562 [Warning] [ComfyUI-0/STDERR] ^^^^^^^^^^^^^^^^^^^^^^
17:43:23.563 [Warning] [ComfyUI-0/STDERR] File "C:\Swarm\SwarmUI\dlbackend\comfy\ComfyUI\server.py", line 50, in cache_control
17:43:23.563 [Warning] [ComfyUI-0/STDERR] response: web.Response = await handler(request)
17:43:23.563 [Warning] [ComfyUI-0/STDERR] ^^^^^^^^^^^^^^^^^^^^^^
17:43:23.564 [Warning] [ComfyUI-0/STDERR] File "C:\Swarm\SwarmUI\dlbackend\comfy\ComfyUI\server.py", line 128, in origin_only_middleware
17:43:23.564 [Warning] [ComfyUI-0/STDERR] response = await handler(request)
17:43:23.564 [Warning] [ComfyUI-0/STDERR] ^^^^^^^^^^^^^^^^^^^^^^
17:43:23.565 [Warning] [ComfyUI-0/STDERR] File "C:\Swarm\SwarmUI\dlbackend\comfy\ComfyUI\server.py", line 619, in post_prompt
17:43:23.565 [Warning] [ComfyUI-0/STDERR] valid = execution.validate_prompt(prompt)
17:43:23.566 [Warning] [ComfyUI-0/STDERR] ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
17:43:23.566 [Warning] [ComfyUI-0/STDERR] File "C:\Swarm\SwarmUI\dlbackend\comfy\ComfyUI\execution.py", line 764, in validate_prompt
17:43:23.566 [Warning] [ComfyUI-0/STDERR] if 'class_type' not in prompt[x]:
17:43:23.567 [Warning] [ComfyUI-0/STDERR] ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
17:43:23.567 [Warning] [ComfyUI-0/STDERR] TypeError: argument of type 'int' is not iterable

[ltdrdata]

It seems that the prompt being passed to ComfyUI is broken.
It looks like you're using SwarmUI, so try updating it to the latest version.

[Jim144a]

I am running the latest version of SwarmUI. I am able to generate images from within the efficient ksampler node and also through the generate tab of Swarm. I only get the error when connecting to the output of the node.

[ltdrdata]

You need to test two things:

1. Try running ComfyUI directly without SwarmUI.
2. Try running ComfyUI with all custom nodes disabled.

One thing to note is that you must execute it using the Python environment provided by SwarmUI.