diff --git a/fet2020/documents/api.py b/fet2020/documents/api.py
index d8190a01..ee6a060a 100644
--- a/fet2020/documents/api.py
+++ b/fet2020/documents/api.py
@@ -15,15 +15,15 @@ def get_ep_client():
 
     # Get api key from settings
     if not os.path.isfile(api_key_path):
-        logger.info(f"API Key file is missing. Path: {api_key_path}")
+        logger.info("API Key file is missing. Path: %s", api_key_path)
         return None
 
-    with open(os.path.abspath(api_key_path), "r") as f:
+    with open(os.path.abspath(api_key_path)) as f:
         api_key = f.read()
         api_key = api_key.rstrip()
 
     if api_key == "":
-        logger.info(f"API Key is missing. Path: {api_key_path}")
+        logger.info("API Key is missing. Path: %s", api_key_path)
         return None
 
     # Connection to Etherpad Client
@@ -36,7 +36,7 @@ def get_ep_client():
             api_version="1.2.14",
         )
     except EtherpadException as e:
-        logger.info(f"Connection to Etherpad Client failed. Error: {e}")
+        logger.info("Connection to Etherpad Client failed. Error: %s", e)
         return None
 
     return ep_c
@@ -56,8 +56,8 @@ def get_ep_group(ep_group_name: str = "fet") -> dict[str, str]:
     return ep_group
 
 
-def ep_pad_exists(pad_id: str | None = None) -> (bool | None):
-    """ Check if pad exists.
+def ep_pad_exists(pad_id: str | None = None) -> bool | None:
+    """Check if pad exists.
 
     Parameters
     ----------
@@ -82,10 +82,10 @@ def ep_pad_exists(pad_id: str | None = None) -> (bool | None):
 
     lists = ep_c.listPads(groupID=ep_group["groupID"])
     if any(pad_id in s for s in lists["padIDs"]):
-        logger.info(f"Etherpad exists. Pad: {pad_id}")
+        logger.info("Etherpad exists. Pad: %s", pad_id)
         return True
 
-    logger.info(f"Etherpad doesn't exist. Pad: {pad_id}")
+    logger.info("Etherpad doesn't exist. Pad: %s", pad_id)
     return False
 
 
@@ -106,13 +106,13 @@ def ep_create_new_pad(pad_id: str | None, text="helloworld"):
 
     if ep_pad_exists(pad_id) is False:
         ep_c.createGroupPad(groupID=ep_group["groupID"], padName=pad_id, text=text)
-        logger.info(f"Create new etherpad. Pad: {pad_id}")
+        logger.info("Create new etherpad. Pad: %s", pad_id)
         return pad_id
 
     return None
 
 
-def ep_get_html(pad_id: str | None) -> (str | None):
+def ep_get_html(pad_id: str | None) -> str | None:
     if (ep_c := get_ep_client()) is None:
         return None
 
diff --git a/fet2020/finance/forms.py b/fet2020/finance/forms.py
index b24265aa..47f856d3 100644
--- a/fet2020/finance/forms.py
+++ b/fet2020/finance/forms.py
@@ -61,7 +61,9 @@ class BillCreateForm(forms.ModelForm):
     iban_text = forms.CharField(required=False, label="IBAN", initial="", max_length=34)
     bic_text = forms.CharField(required=False, label="BIC", initial="", max_length=11)
     saving = forms.BooleanField(
-        required=False, label="Bankdaten für die nächsten Rechnungen speichern.", initial=False
+        required=False,
+        label="Bankdaten für die nächsten Rechnungen speichern.",
+        initial=False,
     )
 
     # Resolution
@@ -138,7 +140,9 @@ class BillUpdateForm(forms.ModelForm):
     iban_text = forms.CharField(required=False, label="IBAN", initial="", max_length=34)
     bic_text = forms.CharField(required=False, label="BIC", initial="", max_length=11)
     saving = forms.BooleanField(
-        required=False, label="Bankdaten für die nächsten Rechnungen speichern.", initial=False
+        required=False,
+        label="Bankdaten für die nächsten Rechnungen speichern.",
+        initial=False,
     )
 
     # only digital bill
@@ -401,7 +405,7 @@ class BillAdminForm(forms.ModelForm):
         qs = qs.filter(status=Wiref.Status.OPENED)
 
         # add wiref id if wiref is already transferred.
-        bill = kwargs.get("instance", None)
+        bill = kwargs.get("instance")
         if bill is not None and bill.wiref is not None and bill.wiref.status != Wiref.Status.OPENED:
             qs |= self.fields["wiref"].queryset.filter(wiref_id=bill.wiref.wiref_id)
 
@@ -425,7 +429,7 @@ class ResolutionAdminForm(forms.ModelForm):
     def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)  # to get the self.fields set
 
-        resolution = kwargs.get("instance", None)
+        resolution = kwargs.get("instance")
         bills = Bill.objects.filter(resolution=resolution)
         total = 0
         for elem in bills:
@@ -475,7 +479,7 @@ class WirefAdminForm(forms.ModelForm):
 
         self.fields["wiref_id"].required = True
 
-        wiref = kwargs.get("instance", None)
+        wiref = kwargs.get("instance")
         total = 0
 
         if wiref is not None:
diff --git a/fet2020/finance/models.py b/fet2020/finance/models.py
index 86009014..741acf7f 100644
--- a/fet2020/finance/models.py
+++ b/fet2020/finance/models.py
@@ -121,7 +121,11 @@ class Wiref(models.Model):
 class Bill(models.Model):
     # members can be deleted but never their bills
     bill_creator = models.ForeignKey(
-        Member, on_delete=models.PROTECT, blank=True, null=True, verbose_name="Verantwortliche:r"
+        Member,
+        on_delete=models.PROTECT,
+        blank=True,
+        null=True,
+        verbose_name="Verantwortliche:r",
     )
 
     bankdata = models.ForeignKey(
diff --git a/fet2020/gallery/management/commands/create_thumbs.py b/fet2020/gallery/management/commands/create_thumbs.py
index 216aaedb..8bacdcf9 100644
--- a/fet2020/gallery/management/commands/create_thumbs.py
+++ b/fet2020/gallery/management/commands/create_thumbs.py
@@ -4,7 +4,6 @@ from django.core.management.base import BaseCommand
 
 from gallery.utils import create_thumbs, get_folder_list
 
-
 logger = logging.getLogger(__name__)
 
 
diff --git a/fet2020/members/templatetags/job_groups.py b/fet2020/members/templatetags/job_groups.py
index 907bbf12..19b43b72 100644
--- a/fet2020/members/templatetags/job_groups.py
+++ b/fet2020/members/templatetags/job_groups.py
@@ -3,7 +3,7 @@ from collections import deque
 from django import template
 from django.db.models import F
 
-from members.models import JobMember, JobGroup
+from members.models import JobGroup, JobMember
 
 register = template.Library()
 
diff --git a/fet2020/posts/models.py b/fet2020/posts/models.py
index b23c37f7..92216211 100644
--- a/fet2020/posts/models.py
+++ b/fet2020/posts/models.py
@@ -131,7 +131,7 @@ class Post(models.Model):
     articles = ArticleManager()
 
     def __str__(self):
-        return "Post (%s, %s): %s" % (
+        return "Post ({}, {}): {}".format(
             self.slug,
             self.public_date.strftime("%d.%m.%Y"),
             self.title,
@@ -151,7 +151,7 @@ class Post(models.Model):
         super().save(*args, **kwargs)
 
     @property
-    def agenda_html(self) -> (str | None):
+    def agenda_html(self) -> str | None:
         "Agenda HTML from Etherpad Pad"
         if self.agenda_key in [None, "#"]:
             return None
@@ -159,7 +159,7 @@ class Post(models.Model):
         return ep_get_html(self.agenda_key)
 
     @property
-    def protocol_html(self) -> (str | None):
+    def protocol_html(self) -> str | None:
         "Protocol HTML from Etherpad Pad"
         if self.protocol_key in [None, "#"]:
             return None
@@ -167,7 +167,7 @@ class Post(models.Model):
         return ep_get_html(self.protocol_key)
 
     @agenda_html.setter
-    def agenda_html(self, value: str) -> (str | None):
+    def agenda_html(self, value: str) -> str | None:
         if self.agenda_key is None:
             self.create_agenda_key()
 
@@ -175,11 +175,11 @@ class Post(models.Model):
             return None
 
         ep_set_html(self.agenda_key, value)
-        request_logger.info(f"Set agenda etherpad. Post: {self.slug}. Key: {self.agenda_key}")
+        request_logger.info("Set agenda etherpad. Post: %s. Key: %s", self.slug, self.agenda_key)
         return value
 
     @protocol_html.setter
-    def protocol_html(self, value: str) -> (str | None):
+    def protocol_html(self, value: str) -> str | None:
         if self.protocol_key is None:
             self.create_protocol_key()
 
@@ -187,14 +187,16 @@ class Post(models.Model):
             return None
 
         ep_set_html(self.protocol_key, value)
-        request_logger.info(f"Set protocol etherpad. Post: {self.slug}. Key: {self.protocol_key}")
+        request_logger.info(
+            "Set protocol etherpad. Post: %s. Key: %s", self.slug, self.protocol_key
+        )
         return value
 
     _agenda_filename = None
     _agenda_url = None
 
     @property
-    def agenda_url(self) -> (str | None):
+    def agenda_url(self) -> str | None:
         if self.has_agenda is not True:
             self._agenda_url = None
             self._agenda_filename = None
@@ -213,7 +215,7 @@ class Post(models.Model):
         return self._agenda_url
 
     @property
-    def agenda_filename(self) -> (str | None):
+    def agenda_filename(self) -> str | None:
         if self._agenda_filename is not None:
             return self._agenda_filename
 
@@ -226,7 +228,7 @@ class Post(models.Model):
     _protocol_url = None
 
     @property
-    def protocol_url(self) -> (str | None):
+    def protocol_url(self) -> str | None:
         if self.has_protocol is not True:
             self._protocol_url = None
             self._protocol_filename = None
@@ -245,7 +247,7 @@ class Post(models.Model):
         return self._protocol_url
 
     @property
-    def protocol_filename(self) -> (str | None):
+    def protocol_filename(self) -> str | None:
         if self._protocol_filename is not None:
             return self._protocol_filename
 
diff --git a/fet2020/posts/templatetags/post_helpers.py b/fet2020/posts/templatetags/post_helpers.py
index e18a74d0..81c93e1c 100644
--- a/fet2020/posts/templatetags/post_helpers.py
+++ b/fet2020/posts/templatetags/post_helpers.py
@@ -11,6 +11,4 @@ register = template.Library()
 @stringfilter
 def tags_to_url(value):
     # return "Tag to url: %s" % value
-    return mark_safe(
-        re.sub(r"\#([\d\w-]+)", r'<a href="/posts/t/\g<1>">#\g<1></a>', value)
-    )
+    return mark_safe(re.sub(r"\#([\d\w-]+)", r'<a href="/posts/t/\g<1>">#\g<1></a>', value))