diff --git a/radicale/__init__.py b/radicale/__init__.py
index 90b0752..39402ba 100644
--- a/radicale/__init__.py
+++ b/radicale/__init__.py
@@ -302,6 +302,23 @@ class Application:
             is_authenticated = self.is_authenticated(user, password)
         is_valid_user = is_authenticated or not user
 
+        # Create principal collection
+        if user and is_authenticated:
+            principal_path = "/%s/" % user
+            if self.authorized(user, self.Collection(principal_path, True),
+                               "w"):
+                with self.Collection.acquire_lock("r"):
+                    principal = next(self.Collection.discover(principal_path),
+                                     None)
+                if not principal or principal.path != principal_path.strip("/"):
+                    with self.Collection.acquire_lock("w"):
+                        # the collection might exist by now
+                        principal = next(self.Collection.discover(
+                            principal_path), None)
+                        if (not principal or
+                                principal.path != principal_path.strip("/")):
+                            self.Collection.create_collection(principal_path)
+
         # Get content
         content_length = int(environ.get("CONTENT_LENGTH") or 0)
         if content_length:
diff --git a/radicale/storage.py b/radicale/storage.py
index dd5290a..e43ebe5 100644
--- a/radicale/storage.py
+++ b/radicale/storage.py
@@ -364,25 +364,27 @@ class Collection(BaseCollection):
         # path should already be sanitized
         sane_path = sanitize_path(path).strip("/")
         attributes = sane_path.split("/")
-        if not attributes:
-            return
+        if not attributes[0]:
+            attributes.pop()
 
         # Try to guess if the path leads to a collection or an item
         folder = os.path.expanduser(
             cls.configuration.get("storage", "filesystem_folder"))
         if not os.path.isdir(path_to_filesystem(folder, sane_path)):
             # path is not a collection
-            if os.path.isfile(path_to_filesystem(folder, sane_path)):
+            if attributes and os.path.isfile(path_to_filesystem(folder,
+                                                                sane_path)):
                 # path is an item
                 attributes.pop()
-            elif os.path.isdir(path_to_filesystem(folder, *attributes[:-1])):
+            elif attributes and os.path.isdir(path_to_filesystem(
+                    folder, *attributes[:-1])):
                 # path parent is a collection
                 attributes.pop()
             # TODO: else: return?
 
         path = "/".join(attributes)
 
-        principal = len(attributes) <= 1
+        principal = len(attributes) == 1
         collection = cls(path, principal)
         yield collection
         if depth != "0":
diff --git a/radicale/xmlutils.py b/radicale/xmlutils.py
index bf3fff9..57552b9 100644
--- a/radicale/xmlutils.py
+++ b/radicale/xmlutils.py
@@ -589,16 +589,17 @@ def _propfind_response(path, item, props, user, write=False):
         is404 = False
         if tag == _tag("D", "getetag"):
             element.text = item.etag
-        elif tag == _tag("D", "principal-URL"):
-            tag = ET.Element(_tag("D", "href"))
-            tag.text = _href(collection, path)
-            element.append(tag)
         elif tag == _tag("D", "getlastmodified"):
             element.text = item.last_modified
-        elif tag in (_tag("D", "principal-collection-set"),
-                     _tag("C", "calendar-user-address-set"),
-                     _tag("CR", "addressbook-home-set"),
-                     _tag("C", "calendar-home-set")):
+        elif tag == _tag("D", "principal-collection-set"):
+            tag = ET.Element(_tag("D", "href"))
+            tag.text = _href(collection, "/")
+            element.append(tag)
+        elif (tag in (_tag("C", "calendar-user-address-set"),
+                      _tag("D", "principal-URL"),
+                      _tag("CR", "addressbook-home-set"),
+                      _tag("C", "calendar-home-set")) and
+                collection.is_principal):
             tag = ET.Element(_tag("D", "href"))
             tag.text = _href(collection, path)
             element.append(tag)