How to Check ComfyUI Workflow JSON
By Elmehdi ยท Updated October 5, 2026
A ComfyUI workflow export describes a graph. It does not include every detail of the environment that runs it. Start by checking the graph structure, then investigate the runtime separately.
UI workflow JSON versus API prompt JSON
A UI export typically contains a nodes array and a links array. Nodes describe the editor graph, while a link records a connection between a source node and a destination node. An API prompt instead uses node IDs as object keys with class_type and inputs fields. OnBeg accepts both formats, including an API prompt wrapped in a prompt property.
Duplicate node IDs
Each node in a UI export should have a distinct ID. If two nodes share an ID, a connection cannot reliably identify which one is intended. Re-export the workflow from ComfyUI first. If the export still contains duplicates, inspect the affected nodes in the editor and recreate the broken part of the graph. Keep a copy of your original file before editing.
Missing connections and orphan references
A link whose source or destination node is absent usually points to an incomplete export or a graph that changed without its links being updated. Find the node ID reported by the checker, compare it with the editor, and reconnect or remove the obsolete link. Do not invent a replacement node based only on its ID: identify the original node type and its required data first.
Socket positions and types
Socket indexes start at zero. When a UI export includes input and output definitions, the checker can flag a link index beyond those definitions. It cannot establish every type compatibility rule or required input without the installed node schemas. In API JSON, a two-item array may be a node connection or a literal value, so a missing-source warning needs manual review.
What a clean report means
No structural issues found means only that the implemented checks did not detect a problem. Check model paths, custom node installations and package versions next, then run the workflow in ComfyUI. OnBeg does not execute or automatically rewrite your file.