remotion-dev/remotion · error · error

could not generate random hash

Error message

could not generate random hash: %w

What it means

Returned by randomHash when crypto/rand.Reader fails to produce a secure random integer. The hash is used as the 10-character suffix of a new S3 bucket name. The crypto/rand source essentially never fails on a healthy Linux/macOS system, so this error almost always indicates the kernel's entropy pool is unavailable (very early boot) or that the OS random device is broken.

Solutions

1. Retry the operation once the host is past early boot; the CRNG initializes quickly.
2. Ensure /dev/urandom is mounted and readable inside the container (`ls -l /dev/urandom`).
3. If it persists, report a host/VM issue to your infrastructure team — this is not an application bug.

var name string
// crypto/rand failures are transient on a cold host; one retry is reasonable.
for attempt := 0; attempt < 2; attempt++ {
    n, err := randomHash()
    if err == nil { name = n; break }
    if attempt == 1 { return err }
}

When it happens

Trigger: rand.Int returns an error because /dev/urandom cannot be read, or the kernel CSPRNG is in a not-yet-initialized state during early boot on a VM/container without getrandom() support.

Common situations: Running the Go binary during container startup before the host's CRNG is initialized. Stripped-down containers that do not mount /dev/urandom. Extremely rare on modern kernels.

Related errors

• could not get location of S3 bucket
• could not list S3 buckets
• could not load AWS config
• failed to create bucket
• failed to upload inputProps to S3

AI-assisted analysis of remotion-dev/remotion@10db9de073 (2026-08-12). Data as JSON: /api/errors/ed2e9bf9a96891d4. Report an issue: GitHub.

Appendix: source

Thrown at packages/lambda-go/s3.go:52

type cancellationObjectClient interface {
	GetObject(context.Context, *s3.GetObjectInput, ...func(*s3.Options)) (*s3.GetObjectOutput, error)
	PutObject(context.Context, *s3.PutObjectInput, ...func(*s3.Options)) (*s3.PutObjectOutput, error)
}

// hashPayload returns the SHA256 hex digest used as the input-props object name.
func hashPayload(payload string) string {
	sum := sha256.Sum256([]byte(payload))
	return hex.EncodeToString(sum[:])
}

// randomHash returns a 10 character [a-z0-9] string used as a bucket suffix.
func randomHash() (string, error) {
	const alphabet = "abcdefghijklmnopqrstuvwxyz0123456789"
	b := make([]byte, 10)
	for i := range b {
		index, err := rand.Int(rand.Reader, big.NewInt(int64(len(alphabet))))
		if err != nil {
			return "", fmt.Errorf("could not generate random hash: %w", err)
		}
		b[i] = alphabet[index.Int64()]
	}
	return string(b), nil
}

// makeBucketName mirrors the JS SDK bucket naming convention.
func makeBucketName(region string) (string, error) {
	suffix, err := randomHash()
	if err != nil {
		return "", err
	}
	return bucketNamePrefix + strings.ReplaceAll(region, "-", "") + "-" + suffix, nil
}

func inputPropsKey(hash string) string {
	return fmt.Sprintf("input-props/%s.json", hash)
}

View on GitHub (pinned to 10db9de073)