diff --git a/src/documents/checks.py b/src/documents/checks.py
index 69027bf21..41f836882 100644
--- a/src/documents/checks.py
+++ b/src/documents/checks.py
@@ -8,6 +8,7 @@ from django.db.utils import OperationalError
 from django.db.utils import ProgrammingError
 
 from documents.signals import document_consumer_declaration
+from documents.templatetags import convert_to_django_template_format
 
 
 @register()
@@ -69,3 +70,17 @@ def parser_check(app_configs, **kwargs):
         ]
     else:
         return []
+
+
+@register()
+def filename_format_check(app_configs, **kwargs):
+    if settings.FILENAME_FORMAT:
+        converted_format = convert_to_django_template_format(settings.FILENAME_FORMAT)
+        if converted_format != settings.FILENAME_FORMAT:
+            return [
+                Error(
+                    f"Filename format {settings.FILENAME_FORMAT} is using the old style, please update to use double curly brackets",
+                    hint=converted_format,
+                ),
+            ]
+    return []
diff --git a/src/documents/file_handling.py b/src/documents/file_handling.py
index 86df569bf..779e1377e 100644
--- a/src/documents/file_handling.py
+++ b/src/documents/file_handling.py
@@ -17,6 +17,7 @@ from documents.models import Document
 from documents.models import DocumentType
 from documents.models import StoragePath
 from documents.models import Tag
+from documents.templatetags import convert_to_django_template_format
 
 logger = logging.getLogger("paperless.filehandling")
 
@@ -112,29 +113,6 @@ def generate_unique_filename(doc, archive_filename=False):
             return new_filename
 
 
-def convert_to_django_template_format(old_format: str) -> str:
-    """
-    Converts old Python string format (with {}) to Django template style (with {{ }}),
-    while ignoring existing {{ ... }} placeholders.
-
-    :param old_format: The old style format string (e.g., "{title} by {author}")
-    :return: Converted string in Django Template style (e.g., "{{ title }} by {{ author }}")
-    """
-
-    # Step 1: Match placeholders with single curly braces but not those with double braces
-    pattern = r"(?<!\{)\{(\w*)\}(?!\})"  # Matches {var} but not {{var}}
-
-    # Step 2: Replace the placeholders with {{ var }} or {{ }}
-    def replace_with_django(match):
-        variable = match.group(1)  # The variable inside the braces
-        return f"{{{{ {variable} }}}}"  # Convert to {{ variable }}
-
-    # Apply the substitution
-    converted_format = re.sub(pattern, replace_with_django, old_format)
-
-    return converted_format
-
-
 def create_dummy_document():
     """
     Create a dummy Document instance with all possible fields filled
@@ -258,26 +236,28 @@ def get_tags_context(tags: Iterable[Tag]) -> dict[str, str | list[str]]:
 
 def get_custom_fields_context(
     custom_fields: Iterable[CustomFieldInstance],
-) -> dict[str, dict[str, str]]:
+) -> dict[str, dict[str, dict[str, str]]]:
     """
     Given an Iterable of CustomFieldInstance, builds a dictionary mapping the field name
     to its type and value
     """
     return {
-        pathvalidate.sanitize_filename(
-            field_instance.field.name,
-            replacement_text="-",
-        ): {
-            "type": pathvalidate.sanitize_filename(
-                field_instance.field.data_type,
+        "custom_fields": {
+            pathvalidate.sanitize_filename(
+                field_instance.field.name,
                 replacement_text="-",
-            ),
-            "value": pathvalidate.sanitize_filename(
-                str(field_instance.value),
-                replacement_text="-",
-            ),
-        }
-        for field_instance in custom_fields
+            ): {
+                "type": pathvalidate.sanitize_filename(
+                    field_instance.field.data_type,
+                    replacement_text="-",
+                ),
+                "value": pathvalidate.sanitize_filename(
+                    str(field_instance.value),
+                    replacement_text="-",
+                ),
+            }
+            for field_instance in custom_fields
+        },
     }
 
 
@@ -401,14 +381,6 @@ def generate_filename(
         filename_format = convert_to_django_template_format(
             settings.FILENAME_FORMAT,
         )
-
-        # Warn the user they should update
-        # TODO: Move this to system check
-        if filename_format != settings.FILENAME_FORMAT:
-            logger.warning(
-                f"Filename format {settings.FILENAME_FORMAT} is using the old style, please update to use double curly brackets",
-            )
-            logger.info(filename_format)
     else:
         filename_format = None
 
diff --git a/src/documents/migrations/1054_alter_storage_path_templates.py b/src/documents/migrations/1054_alter_storage_path_templates.py
index 073fb57b0..796e00b87 100644
--- a/src/documents/migrations/1054_alter_storage_path_templates.py
+++ b/src/documents/migrations/1054_alter_storage_path_templates.py
@@ -10,7 +10,7 @@ def convert_from_format_to_template(apps, schema_editor):
 
     StoragePath = apps.get_model("documents", "StoragePath")
 
-    from documents.file_handling import convert_to_django_template_format
+    from documents.templatetags import convert_to_django_template_format
 
     with transaction.atomic():
         for storage_path in StoragePath.objects.all():
diff --git a/src/documents/serialisers.py b/src/documents/serialisers.py
index e516719ef..fe7c7500e 100644
--- a/src/documents/serialisers.py
+++ b/src/documents/serialisers.py
@@ -29,8 +29,6 @@ from rest_framework import fields
 from rest_framework import serializers
 from rest_framework.fields import SerializerMethodField
 
-from documents.file_handling import convert_to_django_template_format
-
 if settings.AUDIT_LOG_ENABLED:
     from auditlog.context import set_actor
 
@@ -56,6 +54,7 @@ from documents.models import WorkflowTrigger
 from documents.parsers import is_mime_type_supported
 from documents.permissions import get_groups_with_only_permission
 from documents.permissions import set_permissions_for_object
+from documents.templatetags import convert_to_django_template_format
 from documents.validators import uri_validator
 
 logger = logging.getLogger("paperless.serializers")
diff --git a/src/documents/templatetags.py b/src/documents/templatetags.py
index 9a2b4b969..ff9b903d4 100644
--- a/src/documents/templatetags.py
+++ b/src/documents/templatetags.py
@@ -1,3 +1,4 @@
+import os
 import re
 
 from django import template
@@ -26,7 +27,10 @@ class FilePathNode(template.Node):
             """
             value = value.replace("\n", "").replace("\r", "")
             value = re.sub(r"\s*/\s*", "/", value)
-            return value.strip()
+
+            # We remove trailing and leading separators, as these are always relative paths, not absolute, even if the user
+            # tries
+            return value.strip().strip(os.sep)
 
         output = self.nodelist.render(context)
         return clean_filepath(output)
@@ -41,3 +45,26 @@ def construct_filepath(parser, token):
     nodelist = parser.parse(("endfilepath",))
     parser.delete_first_token()
     return FilePathNode(nodelist)
+
+
+def convert_to_django_template_format(old_format: str) -> str:
+    """
+    Converts old Python string format (with {}) to Django template style (with {{ }}),
+    while ignoring existing {{ ... }} placeholders.
+
+    :param old_format: The old style format string (e.g., "{title} by {author}")
+    :return: Converted string in Django Template style (e.g., "{{ title }} by {{ author }}")
+    """
+
+    # Step 1: Match placeholders with single curly braces but not those with double braces
+    pattern = r"(?<!\{)\{(\w*)\}(?!\})"  # Matches {var} but not {{var}}
+
+    # Step 2: Replace the placeholders with {{ var }} or {{ }}
+    def replace_with_django(match):
+        variable = match.group(1)  # The variable inside the braces
+        return f"{{{{ {variable} }}}}"  # Convert to {{ variable }}
+
+    # Apply the substitution
+    converted_format = re.sub(pattern, replace_with_django, old_format)
+
+    return converted_format
diff --git a/src/documents/tests/test_api_objects.py b/src/documents/tests/test_api_objects.py
index 1a55a936c..c74248b9a 100644
--- a/src/documents/tests/test_api_objects.py
+++ b/src/documents/tests/test_api_objects.py
@@ -239,7 +239,7 @@ class TestApiStoragePaths(DirectoriesMixin, APITestCase):
                     "/{created_year_short}/{created_month}/{created_month_name}"
                     "/{created_month_name_short}/{created_day}/{added}/{added_year}"
                     "/{added_year_short}/{added_month}/{added_month_name}"
-                    "/{added_month_name_short}/{added_day}/{asn}/{tags}"
+                    "/{added_month_name_short}/{added_day}/{asn}"
                     "/{tag_list}/{owner_username}/{original_name}/{doc_pk}/",
                 },
             ),
diff --git a/src/documents/tests/test_checks.py b/src/documents/tests/test_checks.py
index 321490396..4288f69f1 100644
--- a/src/documents/tests/test_checks.py
+++ b/src/documents/tests/test_checks.py
@@ -6,6 +6,7 @@ from django.test import TestCase
 from django.test import override_settings
 
 from documents.checks import changed_password_check
+from documents.checks import filename_format_check
 from documents.checks import parser_check
 from documents.models import Document
 from documents.tests.factories import DocumentFactory
@@ -73,3 +74,17 @@ class TestDocumentChecks(TestCase):
                     ),
                 ],
             )
+
+    def test_filename_format_check(self):
+        self.assertEqual(filename_format_check(None), [])
+
+        with override_settings(FILENAME_FORMAT="{created}/{title}"):
+            self.assertEqual(
+                filename_format_check(None),
+                [
+                    Error(
+                        "Filename format {created}/{title} is using the old style, please update to use double curly brackets",
+                        hint="{{ created }}/{{ title }}",
+                    ),
+                ],
+            )