Debug a workflow

Most workflow problems sit at one node. Find the first node whose output is wrong, fix it, and rerun from there. Rerunning the whole graph pays again for every node that was already fine.

Symptom	First thing to check
A wire will not connect	The port colors: they must match
A node fails or stays empty	A required input that is not wired
The output is wrong	The prompt the node actually received
Loops and lists misbehave	The Split Text delimiter
The cost is higher than expected	The group badges, then loops and multiple results
The run is stuck	A paused Approval or Choose node

The isolation method

1Findfirst wrong result, left to right
2IsolateRun This Node
3Change one thingprompt, model, setting or wire
4ContinueRun From Here
5Name itrename or Sticky Note

Read the graph from left to right. Click into each node's result. The first one that looks wrong is your suspect; everything after it inherits the problem.
Run the suspect alone. Hover it and choose Run This Node. Its inputs are the results already on the canvas, so you pay for one node.
Change one thing. The prompt, the model, a setting or a wire. Not three at once.
Continue with Run From Here. When the node is right, run it and everything after it.
Name what you fixed. Rename the node or add a Sticky Note so the next person knows why the setting is what it is.

Hover a node in error to read its message. Scenario's help center lists four node states: pending, running, complete and errored.

A wire will not connect

Cause	Fix
Port types differ	Ports connect by color: Image green, Video yellow, 3D red, Audio purple, Text blue. A blue First Result goes into Prompt, not into Reference Images
You dragged from an input	Wires start at an output (right side) and end at an input (left side)
You need a still from a video	Use the Video Generator's or Video Studio's First Frame or Last Frame output
You need text from an image	Put an LLM Node between them to describe the image

A node fails or stays empty

Fix in this order, cheapest first:

A required input is not wired. Check every port that the node needs. A generator with no Prompt has nothing to do.
The upstream node is empty. It never ran, or it failed. Run it first.
The branch was not taken. An If-Else sent data the other way, or an Approval was rejected. Follow the path the run took.
The input file is unsupported or too large. Use PNG, JPG or WebP for images, MP4 or MOV for video, OBJ, FBX or GLB for 3D.
The model does not accept that combination. Some models ignore reference images, or need a specific aspect ratio or duration. Click the model footer and check its capabilities in Choose a Model, or try a model from the same tab.
The node is inactive. Generators and the LLM Node have an Is Active port. If something is wired into it, check the value it receives.

The output is wrong

Decide first whether the prompt or the model is at fault.

Read the prompt the node actually received. If an LLM Node writes the prompt, run it alone and read First Result. A vague or chatty prompt ("Here is a prompt for you: ...") explains a vague image. Fix the instruction: end it with "Output only the prompt" (LLM Node settings).
Paste the same prompt into the Create page with the same model. If the result is just as wrong there, the brief is the problem. If it is right there, look for a setting or reference that differs in the node.
Swap the model on the same prompt. If a second model gets it right, the first one is a poor fit for the task. See Choose a model.
Check the references. A reference image wired to the wrong input, or the wrong image in a multi-image node, pulls results off brief.

Normal variance is not a bug: the same prompt gives different takes, and an LLM writes a different prompt each run.

To make it repeatable, freeze the parts that must not move: copy a good LLM output into a Text node, and use Prompt Builder for fixed wording.

Loops and lists misbehave

Symptom	Likely cause	Fix
One result instead of many	Split Text delimiter does not match	Change the delimiter; check the chips it shows
Loop does nothing	Input list not connected, or the repeated nodes are not wired between the Loop and its Loop (End)	Wire the list into Input List, the Loop's item into the repeated nodes and the last result into Loop (End)
Fewer items than expected	Slice Items range runs past the end	Expected behavior; adjust From Item and Number of Items
If-Else always picks one side	The first case met wins, or the value is not what you think	Check the order of the cases, the field each condition uses and its operator ("contains" is for text, "=" compares the exact value). Run the upstream node alone and read its exact output

The cost is higher than expected

Read the badges. The badge next to the workflow title is the estimate for one full run; each group shows its share. Find the expensive group.
Look for multipliers. A Loop multiplies by items. Number of Results on an LLM Node, or several outputs on a generator, multiplies every node after it.
Check resolution, quality and duration. Higher settings and longer video cost more.
Move cheap filters before expensive steps. Pick or approve stills before they become video or 3D. See Control cost and Repair at the cheapest stage.

On the runs measured for this Academy, the billed cost came in at or a little under the badge.

The run is stuck

It is waiting for a person. An Approval node or Slice Items in Choose mode is paused. On Slice Items, click Select to Continue.
It is still generating. Video and 3D steps can take minutes. Watch the node states.
Too many runs at once. The API documents 10 concurrent workflow runs per project; later runs wait their turn.

When to contact support

Contact Scenario support when:

The same error repeats on a known-good input after you have checked the wires, the model and the input format;
A run is charged but no output appears;
The billed cost is far above the badge.

Include the workflow ID (... > Copy Workflow ID), the time of the run, the node name and the error text.