What causes "Failed to create bucket %s: %s, previous error: %s" in juicedata/juicefs?

Check both errors: the create error usually reveals the root cause (auth vs network)

Failed to create bucket %s: %s, previous error: %s

Error message

Failed to create bucket %s: %s, previous error: %s

What it means

The initial Put failed, the store's Create (bucket creation) attempt also failed, and the original error was NOT NoSuchBucket — so JuiceFS reports the create-bucket failure together with the original Put error without the manual-creation hint. This indicates a general connectivity/auth problem rather than a missing bucket.

Source

Thrown at cmd/format.go:344

	b := make([]rune, n)
	r := rand.New(rand.NewSource(time.Now().UnixNano()))
	for i := range b {
		b[i] = letters[r.Intn(len(letters))]
	}
	return string(b)
}

func doTesting(ctx context.Context, store object.ObjectStorage, key string, data []byte) error {
	if err := store.Put(ctx, key, bytes.NewReader(data)); err != nil {
		if strings.Contains(strings.ToLower(err.Error()), "denied") {
			return fmt.Errorf("Failed to put: %s", err)
		}
		if err2 := store.Create(ctx); err2 != nil {
			if strings.Contains(err.Error(), "NoSuchBucket") {
				return fmt.Errorf("Failed to create bucket %s: %s, previous error: %s\nPlease create bucket %s manually, then format again.",
					store, err2, err, store)
			} else {
				return fmt.Errorf("Failed to create bucket %s: %s, previous error: %s",
					store, err2, err)
			}
		}
		if err := store.Put(ctx, key, bytes.NewReader(data)); err != nil {
			return fmt.Errorf("Failed to put: %s", err)
		}
	}
	// GLACIER storage class doesn't allow read after write
	if _, ok := ctx.Value(object.TierKey{}).(uint8); ok {
		return nil
	}
	p, err := store.Get(ctx, key, 0, -1)
	if err != nil {
		return fmt.Errorf("Failed to get: %s", err)
	}
	data2, err := io.ReadAll(p)
	_ = p.Close()
	if err != nil {

View on GitHub (pinned to c9a67b23e8)

Solutions

Check both errors: the create error usually reveals the root cause (auth vs network)
Validate credentials with the provider CLI against the same endpoint
Test endpoint reachability: `curl -v https://endpoint`
For S3-compatible stores, confirm the provider supports the ListBuckets/CreateBucket semantics JuiceFS uses

Example fix

// before
--storage-url s3://bucket (endpoint misspelled)
// after
--storage-url s3://bucket --endpoint https://s3.us-east-1.amazonaws.com (correct endpoint)

Defensive patterns

Strategy: try-catch

Validate before calling

// pre-flight: verify auth and endpoint
// aws s3 ls s3://mybucket --endpoint-url $ENDPOINT

Type guard

func isCreateFailed(err error) bool {
    return err != nil && strings.Contains(err.Error(), "Failed to create bucket") && !strings.Contains(err.Error(), "NoSuchBucket")
}

Try / catch

err := doTesting(ctx, store, key, data)
if err != nil && strings.Contains(err.Error(), "previous error") {
    // read both errors; usually credentials or endpoint are wrong
}

Prevention

Verify access/secret keys against the exact endpoint before formatting
Test endpoint connectivity with curl or provider CLI
Avoid proxies that intercept TLS to the object store
Confirm the backend supports bucket-creation semantics if relying on auto-create

When it happens

Trigger: Put fails (network error, auth error, DNS failure) and store.Create also fails — e.g. invalid access keys rejected on both calls, unreachable endpoint, or a backend where Create is unsupported and returns its own error.

Common situations: Wrong access/secret keys; endpoint typo causing connection failures; self-signed cert issues against an S3-compatible store; firewall blocking the endpoint.

Understand the failure class

Background: "API request failed": what wrapped HTTP errors from external APIs mean and how to find the real cause — this error's family across 29 libraries.

Related errors

AI-assisted analysis of juicedata/juicefs@c9a67b23e8 (2026-09-06). Data as JSON: /api/errors/c3973fa5204b3efa. Report an issue: GitHub.