diff --git a/frappe/app.py b/frappe/app.py
index 8f40fcfa82..0d7fdc1fe1 100644
--- a/frappe/app.py
+++ b/frappe/app.py
@@ -5,6 +5,7 @@ import logging
 import os
 
 from werkzeug.exceptions import HTTPException, NotFound
+from werkzeug.local import LocalManager
 from werkzeug.middleware.profiler import ProfilerMiddleware
 from werkzeug.middleware.shared_data import SharedDataMiddleware
 from werkzeug.wrappers import Request, Response
@@ -24,10 +25,13 @@ from frappe.utils import get_site_name, sanitize_html
 from frappe.utils.error import make_error_snapshot
 from frappe.website.serve import get_response
 
+local_manager = LocalManager(frappe.local)
+
 _site = None
 _sites_path = os.environ.get("SITES_PATH", ".")
 
 
+@local_manager.middleware
 @Request.application
 def application(request: Request):
 	response = None
diff --git a/frappe/core/doctype/file/file.py b/frappe/core/doctype/file/file.py
index 1518c72f95..0e28145c9a 100755
--- a/frappe/core/doctype/file/file.py
+++ b/frappe/core/doctype/file/file.py
@@ -78,21 +78,38 @@ class File(Document):
 		self.validate_duplicate_entry()
 
 	def validate(self):
+		if self.is_folder:
+			return
+
 		# Ensure correct formatting and type
 		self.file_url = unquote(self.file_url) if self.file_url else ""
 
+		self.validate_attachment_references()
+
 		# when dict is passed to get_doc for creation of new_doc, is_new returns None
 		# this case is handled inside handle_is_private_changed
 		if not self.is_new() and self.has_value_changed("is_private"):
 			self.handle_is_private_changed()
 
-		if not self.is_folder:
-			self.validate_file_path()
-			self.validate_file_url()
-			self.validate_file_on_disk()
+		self.validate_file_path()
+		self.validate_file_url()
+		self.validate_file_on_disk()
 
 		self.file_size = frappe.form_dict.file_size or self.file_size
 
+	def validate_attachment_references(self):
+		if not self.attached_to_doctype:
+			return
+
+		if self.attached_to_name and not isinstance(self.attached_to_name, str):
+			frappe.throw(_("Attached To Name must be a string"), TypeError)
+
+		if not self.attached_to_field:
+			return
+
+		if not frappe.get_meta(self.attached_to_doctype).has_field(self.attached_to_field):
+			frappe.throw(_("The fieldname you've specified in Attached To Field is invalid"))
+
 	def after_rename(self, *args, **kwargs):
 		for successor in self.get_successors():
 			setup_folder_path(successor, self.name)
diff --git a/frappe/tests/test_zbg_job_sanity_test.py b/frappe/tests/test_zbg_job_sanity_test.py
deleted file mode 100644
index 19dc168c04..0000000000
--- a/frappe/tests/test_zbg_job_sanity_test.py
+++ /dev/null
@@ -1,27 +0,0 @@
-""" smoak tests to check that all registered background jobs execute without error.
-
-Note: Filename is intentional to run this test roughly at end. Don't change."""
-
-import time
-
-import frappe
-from frappe.core.doctype.rq_job.rq_job import RQJob, remove_failed_jobs
-from frappe.tests.utils import FrappeTestCase, timeout
-
-
-class TestScheduledJobSanity(FrappeTestCase):
-	def setUp(self):
-		remove_failed_jobs()
-
-	@timeout(90)
-	def test_bg_jobs_run(self):
-		"""Enqueue all scheduled jobs, wait for finish and verify that none failed."""
-		for scheduled_job_type in frappe.get_all("Scheduled Job Type", pluck="name"):
-			frappe.get_doc("Scheduled Job Type", scheduled_job_type).enqueue(force=True)
-
-		while RQJob.get_list({"filters": [["RQ Job", "status", "in", ("queued", "started")]]}):
-			time.sleep(0.5)
-
-		# Check no failed, if failed print full details
-		failed_jobs = RQJob.get_list({"filters": [["RQ Job", "status", "=", "failed"]]})
-		self.assertEqual(len(failed_jobs), 0, "Jobs failed: " + str(failed_jobs))