diff --git a/weed/filer/abstract_sql/abstract_sql_store.go b/weed/filer/abstract_sql/abstract_sql_store.go
index 69ea8d2ab..9d01bdbba 100644
--- a/weed/filer/abstract_sql/abstract_sql_store.go
+++ b/weed/filer/abstract_sql/abstract_sql_store.go
@@ -129,6 +129,14 @@ func (store *AbstractSqlStore) getTxOrDB(ctx context.Context, fullpath util.Full
 		shortPath = util.FullPath(bucketAndObjectKey[t:])
 	}
 
+	// Dot-prefixed entries directly under /buckets (e.g. .system) are internal
+	// folders, not S3 buckets; keep them in the default table by full path.
+	if strings.HasPrefix(bucket, ".") {
+		bucket = DEFAULT_TABLE
+		shortPath = fullpath
+		return
+	}
+
 	if isValidBucket(bucket) {
 		store.dbsLock.Lock()
 		defer store.dbsLock.Unlock()
diff --git a/weed/filer/abstract_sql/abstract_sql_store_test.go b/weed/filer/abstract_sql/abstract_sql_store_test.go
new file mode 100644
index 000000000..156b84c85
--- /dev/null
+++ b/weed/filer/abstract_sql/abstract_sql_store_test.go
@@ -0,0 +1,53 @@
+package abstract_sql
+
+import (
+	"context"
+	"testing"
+
+	"github.com/seaweedfs/seaweedfs/weed/util"
+)
+
+// The bucket owner index lives at /buckets/.system/owners/<owner>/<bucket>.
+// .system is an internal folder, not an S3 bucket, so getTxOrDB must route it
+// to the default table rather than reject it as an invalid bucket name.
+func TestGetTxOrDBInternalSystemFolder(t *testing.T) {
+	store := &AbstractSqlStore{SupportBucketTable: true}
+	ctx := context.Background()
+
+	cases := []struct {
+		path          string
+		isForChildren bool
+	}{
+		{"/buckets/.system/owners", false},
+		{"/buckets/.system/owners/foo/bucket1", false},
+		{"/buckets/.system/owners/foo", true},
+	}
+	for _, c := range cases {
+		_, bucket, shortPath, err := store.getTxOrDB(ctx, util.FullPath(c.path), c.isForChildren)
+		if err != nil {
+			t.Errorf("getTxOrDB(%s): unexpected error: %v", c.path, err)
+		}
+		if bucket != DEFAULT_TABLE {
+			t.Errorf("getTxOrDB(%s): bucket = %q, want %q", c.path, bucket, DEFAULT_TABLE)
+		}
+		if string(shortPath) != c.path {
+			t.Errorf("getTxOrDB(%s): shortPath = %q, want %q", c.path, shortPath, c.path)
+		}
+	}
+}
+
+func TestGetTxOrDBRealBucket(t *testing.T) {
+	store := &AbstractSqlStore{SupportBucketTable: true, dbs: map[string]bool{"mybucket": true}}
+	ctx := context.Background()
+
+	_, bucket, shortPath, err := store.getTxOrDB(ctx, util.FullPath("/buckets/mybucket/dir/file.txt"), false)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if bucket != "mybucket" {
+		t.Errorf("bucket = %q, want mybucket", bucket)
+	}
+	if string(shortPath) != "/dir/file.txt" {
+		t.Errorf("shortPath = %q, want /dir/file.txt", shortPath)
+	}
+}
diff --git a/weed/filer/arangodb/helpers.go b/weed/filer/arangodb/helpers.go
index 776e6d1b8..cf6575005 100644
--- a/weed/filer/arangodb/helpers.go
+++ b/weed/filer/arangodb/helpers.go
@@ -77,6 +77,11 @@ func extractBucket(fullpath util.FullPath) (string, string) {
 		bucket = bucketAndObjectKey[:t]
 		shortPath = string(util.FullPath(bucketAndObjectKey[t:]))
 	}
+	// Dot-prefixed entries directly under /buckets (e.g. .system) are internal
+	// folders, not S3 buckets; keep them in the default collection.
+	if strings.HasPrefix(bucket, ".") {
+		return "", string(fullpath)
+	}
 	return bucket, shortPath
 }
 
diff --git a/weed/filer/leveldb3/leveldb3_store.go b/weed/filer/leveldb3/leveldb3_store.go
index 439143ceb..564d6eadd 100644
--- a/weed/filer/leveldb3/leveldb3_store.go
+++ b/weed/filer/leveldb3/leveldb3_store.go
@@ -118,6 +118,13 @@ func (store *LevelDB3Store) findDB(fullpath weed_util.FullPath, isForChildren bo
 		shortPath = weed_util.FullPath(bucketAndObjectKey[t:])
 	}
 
+	// Dot-prefixed entries directly under /buckets (e.g. .system) are internal
+	// folders, not S3 buckets; keep them in the default DB by full path.
+	if strings.HasPrefix(bucket, ".") {
+		store.dbsLock.RUnlock()
+		return defaultDB, DEFAULT, fullpath, nil
+	}
+
 	if db, found := store.dbs[bucket]; found {
 		store.dbsLock.RUnlock()
 		return db, bucket, shortPath, nil
diff --git a/weed/filer/ydb/ydb_store.go b/weed/filer/ydb/ydb_store.go
index a5e1850b7..e5d14b5ff 100644
--- a/weed/filer/ydb/ydb_store.go
+++ b/weed/filer/ydb/ydb_store.go
@@ -468,6 +468,12 @@ func (store *YdbStore) getPrefix(ctx context.Context, dir *string) (tablePathPre
 			return
 		}
 
+		// Dot-prefixed entries directly under /buckets (e.g. .system) are internal
+		// folders, not S3 buckets; keep them under the default prefix.
+		if strings.HasPrefix(bucket, ".") {
+			return
+		}
+
 		store.dbsLock.Lock()
 		defer store.dbsLock.Unlock()