diff -r 31412adee482 -r dc6d44e69a70 web/views/calendar.py
--- a/web/views/calendar.py	Wed Jun 03 09:09:33 2009 +0200
+++ b/web/views/calendar.py	Thu Apr 04 13:49:34 2019 +0200
@@ -13,7 +13,6 @@
 from cubicweb.selectors import implements
 from cubicweb.utils import strptime, date_range, todate, todatetime
 from cubicweb.view import EntityView
-from cubicweb.web import ajax_replace_url
 
 _ = unicode
 
@@ -164,13 +163,15 @@
             else:
                 user = None
             the_dates = []
-            tstart = todate(task.start)
+            tstart = task.start
             if tstart:
+                tstart = todate(task.start)
                 if tstart > lastday:
                     continue
                 the_dates = [tstart]
-            tstop = todate(task.start)
+            tstop = task.stop
             if tstop:
+                tstop = todate(tstop)
                 if tstop < firstday:
                     continue
                 the_dates = [tstop]
@@ -260,10 +261,12 @@
         prevdate = curdate - timedelta(31)
         nextdate = curdate + timedelta(31)
         rql = self.rset.printable_rql()
-        prevlink = ajax_replace_url('onemonthcalid', rql, 'onemonthcal',
-                                    year=prevdate.year, month=prevdate.month)
-        nextlink = ajax_replace_url('onemonthcalid', rql, 'onemonthcal',
-                                    year=nextdate.year, month=nextdate.month)
+        prevlink = self.req.build_ajax_replace_url('onemonthcalid', rql, 'onemonthcal',
+                                                   year=prevdate.year,
+                                                   month=prevdate.month)
+        nextlink = self.req.build_ajax_replace_url('onemonthcalid', rql, 'onemonthcal',
+                                                   year=nextdate.year,
+                                                   month=nextdate.month)
         return prevlink, nextlink
 
     def _build_calendar_cell(self, celldate, rows, curdate):
@@ -348,13 +351,15 @@
                 continue
             done_tasks.append(task)
             the_dates = []
-            tstart = todate(task.start)
-            tstop = todate(task.stop)
+            tstart = task.start
+            tstop = task.stop
             if tstart:
+                tstart = todate(tstart)
                 if tstart > lastday:
                     continue
                 the_dates = [tstart]
             if tstop:
+                tstop = todate(tstop)
                 if tstop < firstday:
                     continue
                 the_dates = [tstop]
@@ -513,9 +518,11 @@
         prevdate = curdate - timedelta(7)
         nextdate = curdate + timedelta(7)
         rql = self.rset.printable_rql()
-        prevlink = ajax_replace_url('oneweekcalid', rql, 'oneweekcal',
-                                    year=prevdate.year, week=prevdate.isocalendar()[1])
-        nextlink = ajax_replace_url('oneweekcalid', rql, 'oneweekcal',
-                                    year=nextdate.year, week=nextdate.isocalendar()[1])
+        prevlink = self.req.build_ajax_replace_url('oneweekcalid', rql, 'oneweekcal',
+                                                   year=prevdate.year,
+                                                   week=prevdate.isocalendar()[1])
+        nextlink = self.req.build_ajax_replace_url('oneweekcalid', rql, 'oneweekcal',
+                                                   year=nextdate.year,
+                                                   week=nextdate.isocalendar()[1])
         return prevlink, nextlink