* Changed 404 errors to 400 errors

* Removed duplicate traceback log message
* Now provide string, not Exception, as second tuple item to raise

cms/djangoapps/contentstore/views.py

@@ -455,7 +455,7 @@ def preview_dispatch(request, preview_id, location, dispatch=None):
 
     except ProcessingError:
         log.exception("Module raised an error while processing AJAX request")
-        raise Http404
+        return HttpResponseBadRequest()
 
     except:
         log.exception("error processing ajax call")

common/lib/capa/capa/responsetypes.py

@@ -1237,11 +1237,10 @@ def sympy_check2():
         # Log the error if we are debugging
         msg = 'Error occurred while evaluating CustomResponse'
         log.debug(msg, exc_info=True)
-        log.debug(traceback.format_exc())
 
         # Notify student with a student input error
         _, _, traceback_obj = sys.exc_info()
-        raise ResponseError, ResponseError(err.message), traceback_obj
+        raise ResponseError, err.message, traceback_obj
 
 #-----------------------------------------------------------------------------
 

common/lib/xmodule/xmodule/capa_module.py

@@ -461,7 +461,7 @@ class CapaModule(CapaFields, XModule):
 
         except Exception as err:
             _, _, traceback_obj = sys.exc_info()
-            raise ProcessingError, ProcessingError(err.message), traceback_obj
+            raise ProcessingError, err.message, traceback_obj
 
         after = self.get_progress()
         d.update({

lms/djangoapps/courseware/module_render.py

@@ -10,7 +10,7 @@ from django.conf import settings
 from django.contrib.auth.models import User
 from django.core.urlresolvers import reverse
 from django.http import Http404
-from django.http import HttpResponse
+from django.http import HttpResponse, HttpResponseBadRequest
 from django.views.decorators.csrf import csrf_exempt
 
 from requests.auth import HTTPBasicAuth
@@ -449,10 +449,10 @@ def modx_dispatch(request, dispatch, location, course_id):
         log.exception("Module indicating to user that request doesn't exist")
         raise Http404
 
-    # For XModule-specific errors, we respond with 404
+    # For XModule-specific errors, we respond with 400
     except ProcessingError:
         log.exception("Module encountered an error while prcessing AJAX call")
-        raise Http404
+        return HttpResponseBadRequest()
 
     # If any other error occurred, re-raise it to trigger a 500 response
     except: