temporalio/temporal · error

And requires at least 2 predicates, got %v

Error message

And requires at least 2 predicates, got %v

What it means

The And() constructor in common/predicates builds an AND-composed Predicate from 2+ sub-predicates. It panics when fewer than 2 predicates are passed because an AND of 0 or 1 predicates is meaningless in this library's API contract (callers should use the single predicate directly).

Source

Thrown at common/predicates/and.go:18

package predicates

import (
	"fmt"
)

type (
	AndImpl[T any] struct {
		// TODO: see if we can somehow order arbitrary predicats and store a sorted list
		Predicates []Predicate[T]
	}
)

func And[T any](
	predicates ...Predicate[T],
) Predicate[T] {
	if len(predicates) < 2 {
		panic(fmt.Sprintf("And requires at least 2 predicates, got %v", len(predicates)))
	}

	flattened := make([]Predicate[T], 0, len(predicates))
	for _, p := range predicates {
		switch p := p.(type) {
		case *AndImpl[T]:
			flattened = appendPredicates(flattened, p.Predicates...)
		case *UniversalImpl[T]:
			continue
		case *EmptyImpl[T]:
			return p
		default:
			flattened = appendPredicates(flattened, p)
		}
	}

	switch len(flattened) {
	case 0:

View on GitHub (pinned to bde624efd1)

Solutions

1. Pass at least 2 predicates to And
2. If only one predicate exists, return it directly instead of wrapping in And
3. If the input slice may be empty, return a no-op/true predicate or return an error before calling And

Example fix

// before
pred := predicates.And(items...)
// after
var pred predicates.Predicate[int]
switch len(items) {
case 1:
    pred = items[0]
default:
    pred = predicates.And(items...) // len >= 2 guaranteed by caller
}

if len(preds) < 2 {
    // handle: use preds[0] directly or a defined always-true predicate
    return preds[0]
}
pred := predicates.And(preds...)

func safeAnd[T any](ps ...predicates.Predicate[T]) (p predicates.Predicate[T]) {
    defer func() {
        if recover() != nil { p = fallbackPredicate[T]() }
    }()
    return predicates.And(ps...)
}

When it happens

Trigger: Calling And() or And(p) with zero or one Predicate arguments. e.g. And[int]() or And(isEven).

Common situations: Building predicates programmatically from a dynamically-sized slice that ends up empty or has a single element after filtering; copying an Or(...) call and accidentally leaving one argument.

Related errors

• Or requires at least 2 predicates, got %v
• expect at least one rate limiter
• expect at least one rate limiter
• Current cluster name is empty
• Version increment <= 0 or > 2147483647

AI-assisted analysis of temporalio/temporal@bde624efd1 (2026-09-01). Data as JSON: /api/errors/cd961580d5c4f776. Report an issue: GitHub.