Fix crash on too old time machine date (Z#23245824)

dateutil.parser seems to reject dates with second-precision timezone-offsets, which datetime produces for some dates aroung the year 200. datetime.fromisoformat has no problem parsing them

src/pretix/base/timemachine.py

@@ -21,9 +21,11 @@
 #
 import contextvars
 from contextlib import contextmanager
+from datetime import datetime
 
-from dateutil.parser import parse
+from django.contrib import messages
 from django.utils.timezone import now
+from django.utils.translation import gettext_lazy as _
 
 from pretix.base.auth import has_event_access_permission
 
@@ -34,8 +36,17 @@ timemachine_now_var = contextvars.ContextVar('timemachine_now', default=None)
 def time_machine_now_assigned_from_request(request):
     if hasattr(request, 'event') and f'timemachine_now_dt:{request.event.pk}' in request.session and \
             request.event.testmode and has_event_access_permission(request):
-        request.now_dt = parse(request.session[f'timemachine_now_dt:{request.event.pk}'])
-        request.now_dt_is_fake = True
+        try:
+            request.now_dt = datetime.fromisoformat(request.session[f'timemachine_now_dt:{request.event.pk}'])
+            request.now_dt_is_fake = True
+        except ValueError:
+            del request.session[f'timemachine_now_dt:{request.event.pk}']
+            messages.error(
+                request, _('Invalid date.')
+            )
+            request.now_dt = now()
+            request.now_dt_is_fake = False
+
     else:
         request.now_dt = now()
         request.now_dt_is_fake = False

src/pretix/celery_app.py

@@ -20,6 +20,7 @@
 # <https://www.gnu.org/licenses/>.
 #
 import logging
+import multiprocessing
 import os
 
 from celery import Celery, signals
@@ -54,6 +55,21 @@ def on_task_received(sender, request, **kwargs):
         logger.info(f"Task {request.id} has trace {trace}")
 
 
+@receiver(signals.after_setup_task_logger)
+def on_after_setup_task_logger(sender, logger, loglevel, logfile, format, colorize, **kwargs):
+    # This hack seems to be required to get celery to log internal events from eg billiard/pool.py such as
+    # "worker killed because it used too much memory"
+    # You can test that it is working by starting a celery worker with a low value like
+    # --max-memory-per-child 300000
+    # and then trigger a task. Result should look like this:
+    # [2026-09-23 10:42:26,234: WARNING/ForkPoolWorker-16]: [???:???] child process exiting after exceeding memory limit (394540KiB / 300000KiB)
+    # The ???:??? are likely because by copying the handlers, we are also copying the format, but I was unable to find
+    # a better compatible way.
+    multi_logger = multiprocessing.get_logger()
+    multi_logger.setLevel(logging.WARNING)
+    multi_logger.handlers = logger.handlers
+
+
 @receiver(signals.task_prerun)
 def on_task_prerun(sender, task_id, task, **kwargs):
     from pretix.helpers.logs import local

src/pretix/presale/views/event.py

@@ -41,7 +41,6 @@ from importlib import import_module
 from urllib.parse import urlencode
 
 import isoweek
-from dateutil import parser
 from django import forms
 from django.conf import settings
 from django.contrib import messages
@@ -603,12 +602,17 @@ class EventTimeMachine(EventViewMixin, TemplateView):
             raise PermissionDenied(_('You are not allowed to access time machine mode.'))
         if not request.event.testmode:
             raise PermissionDenied(_('This feature is only available in test mode.'))
+
+        initial = {}
+        if request.session.get(f'timemachine_now_dt:{request.event.pk}', None):
+            try:
+                initial['now_dt'] = datetime.fromisoformat(request.session.get(f'timemachine_now_dt:{request.event.pk}', None))
+            except ValueError:
+                pass
+
         self.timemachine_form = TimemachineForm(
             data=request.method == 'POST' and request.POST or None,
-            initial=(
-                {'now_dt': parser.parse(request.session.get(f'timemachine_now_dt:{request.event.pk}', None))}
-                if request.session.get(f'timemachine_now_dt:{request.event.pk}', None) else {}
-            )
+            initial=initial
         )
 
     def get_context_data(self, **kwargs):
@@ -622,7 +626,7 @@ class EventTimeMachine(EventViewMixin, TemplateView):
             messages.success(self.request, _('Time machine disabled!'))
             return redirect(self.get_success_url())
         elif self.timemachine_form.is_valid():
-            request.session[f'timemachine_now_dt:{request.event.pk}'] = str(self.timemachine_form.cleaned_data['now_dt'])
+            request.session[f'timemachine_now_dt:{request.event.pk}'] = self.timemachine_form.cleaned_data['now_dt'].isoformat()
             return redirect(eventreverse(request.event, "presale:event.index"))
         else:
             return self.get(request)

src/pretix/static/pretixcontrol/js/ui/editor.js

@@ -448,7 +448,6 @@ var editor = {
 			var d = data[i], o
 			editor._add_from_data(d)
 		}
-		editor.fabric.discardActiveObject()
 		editor.fabric.renderAll()
 		editor._update_toolbox_values()
 	},
@@ -957,7 +956,6 @@ var editor = {
 			mtr: true
 		})
 		editor.fabric.add(text)
-		editor.fabric.setActiveObject(text)
 		editor._create_savepoint()
 		return text
 	},
@@ -974,7 +972,6 @@ var editor = {
 		rect.scaleToHeight(126)
 		rect.setControlsVisibility({ mtr: false, mb: false, mt: false, mr: false, ml: false })
 		editor.fabric.add(rect)
-		editor.fabric.setActiveObject(rect)
 		editor._create_savepoint()
 		return rect
 	},
@@ -1012,7 +1009,6 @@ var editor = {
 			mtr: true
 		})
 		editor.fabric.add(rect)
-		editor.fabric.setActiveObject(rect)
 		editor._create_savepoint()
 		$('#version-notice').show()
 		return rect
@@ -1030,7 +1026,6 @@ var editor = {
 		})
 		rect.setControlsVisibility({ mtr: false })
 		editor.fabric.add(rect)
-		editor.fabric.setActiveObject(rect)
 		editor._create_savepoint()
 		return rect
 	},
@@ -1049,7 +1044,6 @@ var editor = {
 		})
 		rect.setControlsVisibility({ mtr: false, mb: false, mt: false, mr: false, ml: false })
 		editor.fabric.add(rect)
-		editor.fabric.setActiveObject(rect)
 		editor._create_savepoint()
 		return rect
 	},