diff --git a/openassessment/__init__.py b/openassessment/__init__.py
index 94916d98f8..e9981371be 100644
--- a/openassessment/__init__.py
+++ b/openassessment/__init__.py
@@ -2,4 +2,4 @@
 Initialization Information for Open Assessment Module
 """
 
-__version__ = '6.0.30'
+__version__ = '6.0.31'
diff --git a/openassessment/staffgrader/staff_grader_mixin.py b/openassessment/staffgrader/staff_grader_mixin.py
index d413b0a4b0..f581914d28 100644
--- a/openassessment/staffgrader/staff_grader_mixin.py
+++ b/openassessment/staffgrader/staff_grader_mixin.py
@@ -459,7 +459,7 @@ def submit_staff_assessment(self, submission_uuid, data, suffix=''):  # pylint:
                 data['overall_feedback'],
                 data.get('assess_type', 'regrade'),
                 self.config_data,
-                self.staff_data,
+                self.staff_assessment_data,
             )
             if self.is_team_assignment():
                 do_team_staff_assessment(*args, team_submission_uuid=submission_uuid)
diff --git a/openassessment/xblock/openassessmentblock.py b/openassessment/xblock/openassessmentblock.py
index 509ea4bbc7..f59bda2bbb 100644
--- a/openassessment/xblock/openassessmentblock.py
+++ b/openassessment/xblock/openassessmentblock.py
@@ -310,11 +310,11 @@ def peer_assessment_data(self, continue_grading=False):
         return PeerAssessmentAPI(self, continue_grading)
 
     @property
-    def self_data(self):
+    def self_assessment_data(self):
         return SelfAssessmentAPI(self)
 
     @property
-    def staff_data(self):
+    def staff_assessment_data(self):
         return StaffAssessmentAPI(self)
 
     @property
diff --git a/openassessment/xblock/ui_mixins/legacy/handlers_mixin.py b/openassessment/xblock/ui_mixins/legacy/handlers_mixin.py
index 56f067bc99..707fac942d 100644
--- a/openassessment/xblock/ui_mixins/legacy/handlers_mixin.py
+++ b/openassessment/xblock/ui_mixins/legacy/handlers_mixin.py
@@ -295,7 +295,7 @@ def failure_response(reason):
                 data['overall_feedback'],
                 self.config_data,
                 self.workflow_data,
-                self.self_data,
+                self.self_assessment_data,
             )
         except ReviewerMustHaveSubmittedException:
             return failure_response('You must submit a response before you can perform a self-assessment.')
@@ -376,7 +376,7 @@ def failure_response(reason):
                 data['overall_feedback'],
                 data.get('assess_type', 'regrade'),
                 self.config_data,
-                self.staff_data,
+                self.staff_assessment_data,
             )
         except (StaffAssessmentRequestError, StaffAssessmentInternalError):
             return failure_response('Your team assessment could not be submitted.')
diff --git a/openassessment/xblock/ui_mixins/mfe/mixin.py b/openassessment/xblock/ui_mixins/mfe/mixin.py
index 374b686903..561b32da8f 100644
--- a/openassessment/xblock/ui_mixins/mfe/mixin.py
+++ b/openassessment/xblock/ui_mixins/mfe/mixin.py
@@ -94,6 +94,10 @@ def get_learner_data(self, data, suffix=""):  # pylint: disable=unused-argument
         if not requested_step:
             return PageDataSerializer(self, context=serializer_context).data
 
+        # Raise error if step is closed
+        elif not self.is_step_open(requested_step):
+            raise OraApiException(400, error_codes.INACCESSIBLE_STEP, f"Inaccessible step: {requested_step}")
+
         # Check to see if user can access this workflow step
         requested_workflow_step = MFE_STEP_TO_WORKFLOW_MAPPINGS[requested_step]
         if not self.workflow_data.has_reached_given_step(
@@ -106,6 +110,39 @@ def get_learner_data(self, data, suffix=""):  # pylint: disable=unused-argument
         serializer_context["requested_step"] = requested_step
         return PageDataSerializer(self, context=serializer_context).data
 
+    def is_step_open(self, step_name):
+        """
+        Determine whether or not the requested step is open
+
+        Return: If the problem is open or not (Bool)
+        Raises: OraApiException if the step name is invalid
+        """
+        step_data = None
+
+        # Users can always view a submission they've previously submitted
+        if step_name == "submission" and self.submission_data.has_submitted:
+            return True
+        # And whether they can get to grades, depends on the workflow being "done"
+        elif step_name == "done":
+            return self.workflow_data.is_done
+
+        # Otherwise, get the info for the current step to determine access
+        if step_name == "submission":
+            step_data = self.submission_data
+        elif step_name == "studentTraining":
+            step_data = self.student_training_data
+        elif step_name == "peer":
+            step_data = self.peer_assessment_data()
+        elif step_name == "self":
+            step_data = self.self_assessment_data
+        elif step_name == "staff":
+            step_data = self.staff_assessment_data
+        else:
+            raise OraApiException(400, error_codes.UNKNOWN_SUFFIX, error_context=f"Bad step name: {step_name}")
+
+        # Return if the step is currently open
+        return not step_data.problem_closed
+
     def _submission_draft_handler(self, data):
         try:
             student_submission_data = data['response']['textResponses']
@@ -146,6 +183,9 @@ def submission(self, data, suffix=""):
         if suffix == handler_suffixes.SUBMISSION_DRAFT:
             return self._submission_draft_handler(data)
         elif suffix == handler_suffixes.SUBMISSION_SUBMIT:
+            # Return an error if the submission step is not open
+            if not self.is_step_open("submission"):
+                raise OraApiException(400, error_codes.INACCESSIBLE_STEP)
             return self._submission_create_handler(data)
         else:
             raise OraApiException(404, error_codes.UNKNOWN_SUFFIX)
@@ -302,8 +342,14 @@ def _assessment_submit_handler(self, data):
         assessment_data = serializer.to_legacy_format(self)
         requested_step = serializer.data['step']
         try:
+            # Block assessing a closed step
+            if not self.is_step_open(requested_step):
+                raise OraApiException(400, error_codes.INACCESSIBLE_STEP, f"Inaccessible step: {requested_step}")
+
+            # Block assessing a cancelled submission
             if self.workflow_data.is_cancelled:
                 raise InvalidStateToAssess()
+
             if requested_step == 'peer':
                 peer_assess(
                     assessment_data['options_selected'],
@@ -320,7 +366,7 @@ def _assessment_submit_handler(self, data):
                     assessment_data['feedback'],
                     self.config_data,
                     self.workflow_data,
-                    self.self_data
+                    self.self_assessment_data
                 )
             elif requested_step == 'studentTraining':
                 corrections = training_assess(
diff --git a/openassessment/xblock/ui_mixins/mfe/page_context_serializer.py b/openassessment/xblock/ui_mixins/mfe/page_context_serializer.py
index ce81b67632..b5907df8e6 100644
--- a/openassessment/xblock/ui_mixins/mfe/page_context_serializer.py
+++ b/openassessment/xblock/ui_mixins/mfe/page_context_serializer.py
@@ -208,7 +208,7 @@ class StepInfoSerializer(Serializer):
     submission = SubmissionStepInfoSerializer(source="submission_data")
     studentTraining = StudentTrainingStepInfoSerializer(source="student_training_data")
     peer = PeerStepInfoSerializer(source="peer_assessment_data")
-    _self = SelfStepInfoSerializer(source="self_data")
+    _self = SelfStepInfoSerializer(source="self_assessment_data")
 
     def get_fields(self):
         # Hack to name one of the output fields "self", a reserved word
diff --git a/openassessment/xblock/ui_mixins/mfe/test_mfe_mixin.py b/openassessment/xblock/ui_mixins/mfe/test_mfe_mixin.py
index 8d91f157ba..7ed74ef15c 100644
--- a/openassessment/xblock/ui_mixins/mfe/test_mfe_mixin.py
+++ b/openassessment/xblock/ui_mixins/mfe/test_mfe_mixin.py
@@ -681,6 +681,14 @@ def test_create_submission(self, xblock):
             assert resp.status_code == 200
             assert_called_once_with_helper(mock_submit, self.DEFAULT_SUBMIT_VALUE["submission"]["textResponses"], 3)
 
+    @patch("openassessment.xblock.ui_mixins.mfe.mixin.MfeMixin.is_step_open")
+    @scenario("data/basic_scenario.xml")
+    def test_blocks_submit_when_step_closed(self, xblock, mock_is_step_open):
+        mock_is_step_open.return_value = False
+        with self._mock_create_submission():
+            resp = self.request_create_submission(xblock)
+            assert_error_response(resp, 400, error_codes.INACCESSIBLE_STEP)
+
 
 @ddt.ddt
 class FileUploadTest(MFEHandlersTestBase):
@@ -1012,3 +1020,17 @@ def test_training_assess_corrections(self, xblock):
                 resp = self.request_assessment_submit(xblock, step='studentTraining')
 
         assert_error_response(resp, 400, error_codes.TRAINING_ANSWER_INCORRECT, corrections)
+
+    @patch("openassessment.xblock.ui_mixins.mfe.mixin.MfeMixin.is_step_open")
+    @ddt.data('self', 'studentTraining', 'peer')
+    @scenario("data/basic_scenario.xml")
+    def test_blocks_assess_when_step_closed(self, xblock, mfe_step, mock_is_step_open):
+        mock_is_step_open.return_value = False
+        with self.mock_assess_functions() as assess_mocks:
+            with self.mock_workflow_status(mfe_step):
+                resp = self.request_assessment_submit(xblock, step=mfe_step)
+
+        assert_error_response(resp, 400, error_codes.INACCESSIBLE_STEP, f"Inaccessible step: {mfe_step}")
+        assess_mocks.self.assert_not_called()
+        assess_mocks.training.assert_not_called()
+        assess_mocks.peer.assert_not_called()
diff --git a/package-lock.json b/package-lock.json
index e84ea41c38..f5d617a0e8 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,12 +1,12 @@
 {
   "name": "edx-ora2",
-  "version": "6.0.30",
+  "version": "6.0.31",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "edx-ora2",
-      "version": "6.0.29",
+      "version": "6.0.31",
       "dependencies": {
         "@edx/frontend-build": "8.0.6",
         "@openedx/paragon": "^21.5.7",
diff --git a/package.json b/package.json
index 62a3390f9d..4124e4ea4c 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "edx-ora2",
-  "version": "6.0.30",
+  "version": "6.0.31",
   "repository": "https://github.com/openedx/edx-ora2.git",
   "dependencies": {
     "@edx/frontend-build": "8.0.6",