Fixing ComfyUI Workflow JSON Import Failures for LTX 2.3

You download an LTX 2.3 workflow from a forum post, a Discord channel, or a YouTube description, drag it into ComfyUI, and instead of a working graph you get one of three bad outcomes: a hard error, a blank canvas, or a mess of red nodes. All three trace back to a small set of causes, and all three are fixable in a few minutes once you know which one you're looking at.

The three failure modes

1. Hard failure with an error dialog. ComfyUI throws something like "Loading aborted due to error reloading workflow data" and refuses to load anything. This is a JavaScript exception thrown while the frontend tries to configure the graph from the JSON, and it's almost always caused by a version mismatch: either the ComfyUI frontend package is older than what a custom node extension expects, or a custom node's JS widget code chokes on a node type it doesn't recognize in its current form. The dialog itself usually names the offending script in the stack trace (something like an extension's .js file) — that name is your first clue.

2. Partial load with red or broken nodes. The graph loads, but some nodes appear as red placeholder boxes, or connections are missing. This means ComfyUI parsed the JSON fine but couldn't resolve one or more node types — almost always because you're missing the custom node pack that provides them, most commonly Lightricks/ComfyUI-LTXVideo itself, or a dependency it relies on (video helpers, upscalers, custom samplers). Unlike the hard failure above, this one is graceful: ComfyUI shows you what's missing instead of refusing outright.

3. Silent no-op. You drop the file in, ComfyUI reports success, and... nothing happens, or the canvas stays empty. This is less common but has been reported on fresh installs and newer ComfyUI builds, and it's usually a symptom of dragging the wrong kind of JSON into the wrong place — see below.

Fix checklist

1. Confirm you're importing the right JSON format the right way. ComfyUI has two JSON export shapes floating around: the full "workflow" JSON (with UI layout, node positions, and version metadata) that you drag-and-drop directly onto the canvas, and the older "API-format" JSON meant for the /prompt API or a specific "Load API workflow" menu action. Dragging an API-format export onto the canvas — or using the wrong menu item for a UI-format export — is a very common mistake and can produce anything from a silent no-op to a hard error. Check which one you have before doing anything else.

2. Update ComfyUI and ComfyUI-LTXVideo to matching, recent versions. Version skew between the ComfyUI frontend and the custom node packs a workflow depends on is the single most cited cause of the "reloading workflow data" crash. If the workflow was exported from a recent Lightricks build and you're on an older ComfyUI or an older copy of the LTXVideo node pack, update both through ComfyUI Manager (or git pull if you're managing nodes manually) so they're in step.

3. Hard refresh and clear cached frontend state. ComfyUI's web frontend caches JS, extension state, and sometimes stale localStorage entries from previous sessions. A hard refresh (Ctrl/Cmd+Shift+R) or clearing localStorage for the ComfyUI origin clears out stale UI state that can trigger configure-step exceptions unrelated to the workflow file itself.

4. Open the browser dev console and read the actual error. The dialog text is generic; the real error and stack trace live in the console (F12 → Console tab). It will typically name the extension or script that threw, which tells you exactly what to update, reinstall, or temporarily disable to isolate the problem.

5. Reinstall or update any custom nodes flagged as missing. For red-node partial loads, ComfyUI (or ComfyUI Manager) will list the missing node type names directly. Install the corresponding pack — for LTX 2.3 workflows this is almost always Lightricks/ComfyUI-LTXVideo plus whatever auxiliary nodes (video combine/save, upscale, etc.) the original author used — and check ComfyUI's startup log for "IMPORT FAILED" entries, which point to a Python dependency problem rather than a missing file.

6. Disable custom nodes one by one if the crash persists. If updating everything doesn't resolve a hard failure, the fastest way to isolate a broken extension is to disable custom node packs individually (or all at once, then re-enable in batches) and retry the import until the crash stops.

Run through our full setup steps in the guide if any of this is unfamiliar territory — it covers getting ComfyUI, the LTXVideo nodes, and models into a consistent state before you start importing other people's workflows.

When none of that works: stop importing, start generating

Someone else's exported workflow JSON is a snapshot of their ComfyUI version, their node pack versions, and their model paths at export time. If you've gone through the checklist above and it still won't load cleanly, the fastest fix isn't more debugging — it's not using that file at all. Our workflow generator builds a fresh LTX 2.3 workflow JSON matched to your actual VRAM and model choice, so there's no version drift to fight. If you want something pre-built and verified instead, our curated workflow library has known-good templates for common LTX 2.3 setups that are tested against current ComfyUI and node-pack versions rather than whatever was current when a random export was made.

Sources

• Loading aborted due to error reloading workflow data · Issue #6014 · Comfy-Org/ComfyUI_frontend
• Loading aborted due to error reloading workflow data · Issue #4192 · comfyanonymous/ComfyUI
• Loading aborted due to error reloading workflow data · Issue #1381 · Comfy-Org/ComfyUI
• Loading aborted due to error reloading workflow data (VideoHelperSuite) · Issue #390 · Kosinkadink/ComfyUI-VideoHelperSuite
• Can't load workflows after fresh install that contains missing nodes · Issue #11260 · Comfy-Org/ComfyUI
• Fix ComfyUI Missing Models, Missing Nodes & Import-Failed Errors – RunComfy
• Lightricks/ComfyUI-LTXVideo