columns.schema is required when columns.mappingMode is defineBelow — What This n8n Error Actually Means

Description and use

n8n error occurs when Google Sheets node in defineBelow mode lacks schema. Fixes: re‑select sheet in UI, switch to autoMapInputData, or programmatically build schema.

Problem

Google Sheets node fails with error "columns.schema is required when columns.mappingMode is defineBelow" when workflow JSON is imported or created via API, because the schema field is missing.

Outcome

Node runs successfully after schema is regenerated or mapping mode changed; importers avoid error by re‑selecting sheet or generating schema programmatically.

Workflow

• Open failing node in editor
• Ensure Document and Sheet fields are set to "From list" and re‑select spreadsheet and tab
• Verify mapping remains populated
• Save and run
• (Optional) Switch mappingMode to "autoMapInputData" and clear value map
• (Optional) Programmatically generate schema from header array and inject into node before workflow execution

Evidence

columns.schema is required when columns.mappingMode is defineBelow

Source

Fix 1 — re-select the document and sheet (recommended, about ten seconds)

Source

Fix 3 — build the schema yourself

Source