Fix n8n Workflow Validation Errors

This skill provides expert guidance for interpreting and fixing n8n validation errors, built around the insight that validation is inherently iterative, not one-shot - expect 2-3 validate-fix cycles, with telemetry showing an average of 23 seconds thinking about errors and 58 seconds fixing them per round. It classifies validation output into three severity levels: Errors (block workflow execution and must be resolved - missing_required, invalid_value, type_mismatch, invalid_reference, invalid_expression), Warnings (don't block execution but should be addressed - best_practice, deprecated, performance), and Suggestions (optional improvements - optimization, alternative).

// Iteration 1: validate_node → Error: Missing "name"
// Iteration 2: config.name = "general"; validate_node → Error: Missing "text"
// Iteration 3: config.text = "Hello!"; validate_node → Valid!

A telemetry-observed pattern (7,841 occurrences) documents the normal validate-fix loop: configure a node, call validate_node, read error messages, fix them, and repeat until valid - explicitly framed as normal rather than a sign something is wrong. Four validation profiles are covered with guidance on when to use each: minimal (fastest, checks only required fields and basic structure - for quick edit-time checks), runtime (the recommended default - checks required fields, value types, allowed values, and basic dependencies, balancing thoroughness and noise), ai-friendly (same checks as runtime but more tolerant of minor issues, reducing false positives for AI-generated configurations), and strict (validates everything including best practices, performance, and security - for production/critical workflows, at the cost of more false positives).

For each common error type, it gives the meaning and concrete fix: missing_required (use get_node to find required fields and add them), invalid_value (check the error message for allowed values and update accordingly), type_mismatch (convert the value to the expected type, e.g. string to number), and invalid_expression (cross-reference the n8n Expression Syntax skill, check for missing {{}} or typos in node/field references).

Use it when interpreting or fixing validate_node output for an n8n workflow, especially when stuck in a validation loop or unsure which validation profile fits the current stage of work (editing, AI-generated config, or production deployment). Choose runtime as the default profile for most cases, reserving minimal for quick edit-time checks and strict for production/critical workflows.

Input is validate_node output (an error, warning, or suggestion object) for an n8n workflow node. Output is a diagnosis of the error type and a concrete configuration fix, plus a recommended validation profile for the current stage of work.

Works with n8n's validate_node/get_node tooling and cross-references the n8n Expression Syntax skill for invalid_expression errors specifically.

n8n workflow builders debugging validation errors who need to understand error severity, pick the right validation profile, and fix common error types without getting discouraged by the normal iterative validate-fix process.