Upgraded to most recent Flask-Principal version, since an attribute name was changed there which OctoPrint uses

octoprint/server.py

@@ -610,7 +610,7 @@ def logout():
 
 @identity_loaded.connect_via(app)
 def on_identity_loaded(sender, identity):
-	user = load_user(identity.name)
+	user = load_user(identity.id)
 	if user is None:
 		return
 

octoprint/users.py

@@ -232,4 +232,4 @@ class DummyIdentity(Identity):
 		Identity.__init__(self, "dummy")
 
 def dummy_identity_loader():
-	return DummyIdentity()
+	return DummyIdentity()

requirements.txt

@@ -5,4 +5,4 @@ tornado>=2.4.1
 tornadio2>=0.0.4
 PyYAML>=3.10
 Flask-Login>=0.1.3
-Flask-Principal>=0.3.4
+Flask-Principal>=0.3.5