n8n-io/n8n · warning · OperationalError

Missing 'valueString' for 'like' operator.

Error message

Missing 'valueString' for 'like' operator.

What it means

OperationalError from buildFilter when a Weaviate filter unit uses operator 'like' but valueString is undefined. The like operator requires a string pattern, so n8n refuses to build the filter rather than sending an invalid query.

Source

Thrown at packages/@n8n/nodes-langchain/nodes/vector_store/VectorStoreWeaviate/Weaviate.utils.ts:80

	valueNumber?: number;
	valueGeoCoordinates?: GeoRangeFilter;
};

export type WeaviateCompositeFilter = { AND: WeaviateFilterUnit[] } | { OR: WeaviateFilterUnit[] };

function buildFilter(filter: WeaviateFilterUnit): FilterValue {
	const { path, operator } = filter;
	const property = weaviate.filter.byProperty(path[0]);

	switch (operator.toLowerCase()) {
		case 'equal':
			if (filter.valueString !== undefined) return property.equal(filter.valueString);
			if (filter.valueNumber !== undefined) return property.equal(filter.valueNumber);
			break;

		case 'like':
			if (filter.valueString === undefined) {
				throw new OperationalError("Missing 'valueString' for 'like' operator.");
			}
			return property.like(filter.valueString);

		case 'containsany':
			if (filter.valueTextArray === undefined) {
				throw new OperationalError("Missing 'valueTextArray' for 'containsAny' operator.");
			}
			return property.containsAny(filter.valueTextArray);

		case 'containsall':
			if (filter.valueTextArray === undefined) {
				throw new OperationalError("Missing 'valueTextArray' for 'containsAll' operator.");
			}
			return property.containsAll(filter.valueTextArray);

		case 'greaterthan':
			if (filter.valueNumber === undefined) {
				throw new OperationalError("Missing 'valueNumber' for 'greaterThan' operator.");

View on GitHub (pinned to 5ac6606e81)

Solutions

  1. Provide filter.valueString for any 'like' filter, e.g. { operator: 'like', path: ['title'], valueString: 'news*' }.
  2. If the value is genuinely empty, remove that filter unit or pick an operator that does not need a value.
  3. Validate the filter object shape before the workflow runs the Weaviate node.

Example fix

// before: { operator: 'like', path: ['title'] }
// after:  { operator: 'like', path: ['title'], valueString: 'repo*' }
Defensive patterns

Strategy: validation

Validate before calling

function assertLikeFilter(f: WeaviateFilterUnit) { if (f.operator.toLowerCase() === 'like' && f.valueString === undefined) throw new Error("'like' requires valueString"); }

Type guard

function isLikeFilterComplete(f: WeaviateFilterUnit): f is WeaviateFilterUnit & { operator: 'like'; valueString: string } { return f.operator.toLowerCase() === 'like' && typeof f.valueString === 'string'; }

Try / catch

try { buildFilter(unit) } catch (e) { if (/Missing 'valueString' for 'like'/.test(e.message)) { /* prompt user for the like pattern */ } else throw e; }

Prevention

When it happens

Trigger: A Weaviate metadata filter is supplied as { operator: 'like', path: [...], /* valueString missing */ }. buildFilter switches on operator.toLowerCase() === 'like', finds filter.valueString === undefined, and throws.

Common situations: UI/expression produced a filter object with the 'like' operator but the value field was left empty or mapped to an undefined expression; JSON filter pasted without the valueString key; downstream parameter mapping dropped the field.

Related errors

AI-assisted analysis of n8n-io/n8n@5ac6606e81 (2026-08-12). Data as JSON: /api/errors/104fbb3a5a7caad0. Report an issue: GitHub.