Error codes — Wayflow

Every WayflowError code the runtime and editor can raise — the message and the actionable hint for each.

Every error and validation warning carries a stable code — a WF_… string you can branch on or search your logs for. Compare it against the exact string:

handle.ts ts

if (error.code === 'WF_LLM_MODEL_NOT_FOUND') {
  // …
}

Each code’s message is technical (the literal text the runtime emits, with {placeholders} filled at runtime); its hint, when present, is the actionable suggestion surfaced to the user. See Debugging & diagnostics for how these appear.

Runtime

Code	Message	Hint
`WF_RUNTIME_NO_HANDLER`	`No handler registered for node type "{nodeType}"`	—
`WF_RUNTIME_HANDLER_THREW`	`{reason}` (the handler’s own thrown message)	—
`WF_RUNTIME_EMPTY_GRAPH`	`Graph has no nodes`	—
`WF_RUNTIME_CYCLE_DETECTED`	`Graph contains a cycle ({path}). Cyclic execution is not supported in v1.`	—
`WF_RUNTIME_UNSCHEDULABLE_GRAPH`	`Graph is unschedulable (disconnected or already-failed dependency)`	—
`WF_RUNTIME_MULTIPLE_NODES_FAILED`	`{count} nodes failed: {summary}`	—
`WF_RUNTIME_MISSING_INPUT`	`Input "{field}" is required`	Provide a value or a default for this input, or make it not required.
`WF_AGENT_UNKNOWN_NODE_TYPE`	`Unknown node type "{type}"`	—
`WF_RUNTIME_INVALID_REGEX`	`Conditional 'matches' has an invalid regex pattern "{pattern}": {reason}`	Fix the regex pattern in this node’s config.
`WF_RUNTIME_MULTI_PORT_MISMATCH`	`Handler for node type "{nodeType}" returned a single value, but the node has {portCount} output ports ({portList}). Multi-port handlers must return an object keyed by port id.`	—
`WF_RUNTIME_MAP_MULTIPLE_LISTS`	`This node runs once per item but received more than one list.`	Combine the lists into one with a Merge node so this node gets a single list.
`WF_RUNTIME_MAP_SUSPEND`	`A node that runs once per item tried to pause for human review, which isn't supported mid-iteration.`	Move the Human Review node before or after the per-item node.
`WF_RUNTIME_HTTP_ERROR`	`HTTP {status}: {detail}`	—
`WF_RUNTIME_TOOL_NO_NAME`	`Workflow has no name`	Name the workflow in the editor’s Settings so it can be used as a tool.
`WF_RUNTIME_TOOL_NOT_REGISTERED`	`Graph references tool "{name}" but no handler is registered`	Remove this tool from the node’s Tools list.
`WF_RUNTIME_CHECKPOINT_STALE`	`Can't resume: the graph's structure changed since this checkpoint was created. A checkpoint can only resume against the same nodes, ports, and connections it paused on (editing a node's config is fine; adding, removing, or rewiring nodes is not).`	—
`WF_RUNTIME_PAUSE_IN_TOOL`	`A workflow used as a tool tried to pause for human review, which a tool call cannot do.`	Remove the Human Review node from a workflow that runs as a tool.
`WF_RUNTIME_REVIEW_NOT_RESUMABLE`	`This workflow has a human review step, but the editor isn't set up to handle it.`	—
`WF_RUNTIME_RECURSION_LIMIT`	`Workflows-as-tools nested too deeply. A workflow may be calling itself as a tool.`	—

LLM

Code	Message	Hint
`WF_LLM_MODEL_NOT_FOUND`	`No handler registered for model "{model}"`	Pick an available model in this node’s config.
`WF_LLM_OUTPUT_WRONG_TYPE`	`The model handler returned {type}, but this node has a structured output schema`	—
`WF_LLM_OUTPUT_INVALID_JSON`	`The model returned text that isn't valid JSON: {reason}`	Increase Max Tokens if the output was cut off, ask for JSON explicitly in the prompt, or try a different model.
`WF_LLM_OUTPUT_TRUNCATED`	`The model hit its output-token limit before completing the structured response`	Increase Max Tokens in this node’s config.
`WF_LLM_OUTPUT_NOT_OBJECT`	`The model returned JSON that isn't an object`	Adjust the prompt to return a JSON object keyed by field name.
`WF_LLM_OUTPUT_MISSING_FIELD`	`The model's output is missing the required field "{field}" (expected: {expectedKeys})`	Make sure the prompt asks the model to return every field in the output schema.
`WF_TEMPLATE_VAR_MISSING`	`Template variable "{name}" has no value`	Connect an input to this variable’s port, or set a default value in the node config.
`WF_LLM_IMAGE_URL_UNSUPPORTED`	`This model doesn't accept image URLs, only uploaded (base64) images`	Upload the image instead of pasting a URL.

Image generation

Code	Message	Hint
`WF_IMAGE_MODEL_NOT_FOUND`	`No handler registered for model "{model}"`	Pick an available model in this node’s config.
`WF_IMAGE_GENERATION_FAILED`	`Image generation failed: {reason}`	Check the model name and that the requested size is supported by the backend (some models accept only specific dimensions).
`WF_IMAGE_NO_OUTPUT`	`The image backend returned no image`	Verify the selected model supports image generation.

Validation (Issues tab)

Code	Message	Hint
`WF_VALIDATION_ORPHAN_NODE`	`This node isn't connected to anything`	Connect it to the rest of the workflow, or remove it.
`WF_VALIDATION_NO_INPUT_NODE`	`The workflow has no Input node`	Add an Input node so the workflow can receive data.
`WF_VALIDATION_NO_OUTPUT_NODE`	`The workflow has no Output node`	Add an Output node so the run produces a result.
`WF_VALIDATION_VAR_UNSET`	`Template variable "{name}" has no input — it will be blank in the prompt`	Connect its port, or give it a value under Variable Defaults.
`WF_VALIDATION_VAR_INVALID_NAME`	`Variable "{name}" can't contain spaces`	Use letters, numbers, and underscores instead — for example, image_1.
`WF_VALIDATION_LLM_NO_PROMPT`	`This LLM node has no prompt`	Write a prompt or system prompt so the model has something to act on.
`WF_VALIDATION_IMAGE_NO_PROMPT`	`This Image Generation node has no prompt`	Write a prompt describing the image to generate.
`WF_VALIDATION_TOOL_NOT_IN_CATALOG`	`Tool "{name}" is not in the editor catalog`	Remove it from this node’s Tools list.
`WF_VALIDATION_OUTPUT_FIELD_MISSING`	`Output field "{name}" wasn't produced by the last run`	Connect an input to this field’s port.
`WF_VALIDATION_OUTPUT_TYPE_MISMATCH`	`Output field "{name}" expected {expected}, got {actual}`	—
`WF_VALIDATION_DUPLICATE_UNIQUE_NODE`	`A workflow can have only one {label} node`	Keep only one.