diff --git a/erpnext/accounts/doctype/pos_invoice/pos_invoice.py b/erpnext/accounts/doctype/pos_invoice/pos_invoice.py
index a51b27f4b71..23ef9099b6d 100644
--- a/erpnext/accounts/doctype/pos_invoice/pos_invoice.py
+++ b/erpnext/accounts/doctype/pos_invoice/pos_invoice.py
@@ -6,7 +6,7 @@ import frappe
 from frappe import _, bold
 from frappe.model.document import Document
 from frappe.model.mapper import map_child_doc, map_doc
-from frappe.query_builder.functions import IfNull, Sum
+from frappe.query_builder.functions import IfNull, Lower, Sum
 from frappe.utils import cint, flt, get_link_to_form, getdate, nowdate
 from frappe.utils.nestedset import get_descendants_of
 
@@ -505,16 +505,20 @@ class POSInvoice(SalesInvoice):
 			if d.get("serial_no"):
 				serial_nos = get_serial_nos(d.serial_no)
 				for sr in serial_nos:
-					serial_no_exists = frappe.get_all(
-						"POS Invoice Item",
-						filters={"parent": self.return_against},
-						or_filters=[
-							["serial_no", "=", sr],
-							["serial_no", "like", f"{sr}\n%"],
-							["serial_no", "like", f"%\n{sr}"],
-							["serial_no", "like", f"%\n{sr}\n%"],
-						],
-						limit=1,
+					POI = frappe.qb.DocType("POS Invoice Item")
+					s = sr.lower()
+					serial_no_exists = (
+						frappe.qb.from_(POI)
+						.select(POI.name)
+						.where(POI.parent == self.return_against)
+						.where(
+							(Lower(POI.serial_no) == s)
+							| Lower(POI.serial_no).like(f"{s}\n%")
+							| Lower(POI.serial_no).like(f"%\n{s}")
+							| Lower(POI.serial_no).like(f"%\n{s}\n%")
+						)
+						.limit(1)
+						.run()
 					)
 
 					if not serial_no_exists:
diff --git a/erpnext/controllers/queries.py b/erpnext/controllers/queries.py
index 2ae16c19d17..1903bc43bcb 100644
--- a/erpnext/controllers/queries.py
+++ b/erpnext/controllers/queries.py
@@ -10,7 +10,7 @@ from frappe import qb, scrub
 from frappe.desk.reportview import get_filters_cond, get_match_cond
 from frappe.permissions import has_permission
 from frappe.query_builder import Case, Criterion, DocType
-from frappe.query_builder.functions import Concat, CustomFunction, Length, Locate, Substring, Sum
+from frappe.query_builder.functions import Concat, CustomFunction, Length, Locate, Lower, Substring, Sum
 from frappe.utils import nowdate, today, unique
 from pypika import Order
 
@@ -313,11 +313,19 @@ def item_query(
 		.where(date_condition)
 		.where(Criterion.any(search_conditions))
 		.orderby(
-			Case().when(Locate(txt_no_percent, item.name) > 0, Locate(txt_no_percent, item.name)).else_(99999)
+			Case()
+			.when(
+				Locate(Lower(txt_no_percent), Lower(item.name)) > 0,
+				Locate(Lower(txt_no_percent), Lower(item.name)),
+			)
+			.else_(99999)
 		)
 		.orderby(
 			Case()
-			.when(Locate(txt_no_percent, item.item_name) > 0, Locate(txt_no_percent, item.item_name))
+			.when(
+				Locate(Lower(txt_no_percent), Lower(item.item_name)) > 0,
+				Locate(Lower(txt_no_percent), Lower(item.item_name)),
+			)
 			.else_(99999)
 		)
 		.orderby(item.idx, order=Order.desc)
@@ -406,7 +414,13 @@ def get_project_name(
 	# ordering
 	if txt:
 		# project_name containing search string 'txt' will be given higher precedence
-		q = q.orderby(ifelse(Locate(txt, proj.project_name) > 0, Locate(txt, proj.project_name), 99999))
+		q = q.orderby(
+			ifelse(
+				Locate(Lower(txt), Lower(proj.project_name)) > 0,
+				Locate(Lower(txt), Lower(proj.project_name)),
+				99999,
+			)
+		)
 	q = q.orderby(proj.idx, order=Order.desc).orderby(proj.name)
 
 	if page_len:
diff --git a/erpnext/crm/report/lead_conversion_time/lead_conversion_time.py b/erpnext/crm/report/lead_conversion_time/lead_conversion_time.py
index d7d964d690a..ee0fc3e75d1 100644
--- a/erpnext/crm/report/lead_conversion_time/lead_conversion_time.py
+++ b/erpnext/crm/report/lead_conversion_time/lead_conversion_time.py
@@ -124,7 +124,7 @@ def get_communication_details(filters):
 				FROM
 					`tabCommunication`
 				WHERE
-					recipients  = %s
+					recipients  = %s AND communication_date IS NOT NULL
 				ORDER BY
 					communication_date
 				LIMIT 1
diff --git a/erpnext/stock/doctype/pick_list/pick_list.py b/erpnext/stock/doctype/pick_list/pick_list.py
index d87e815127a..a793d75f6c4 100644
--- a/erpnext/stock/doctype/pick_list/pick_list.py
+++ b/erpnext/stock/doctype/pick_list/pick_list.py
@@ -9,7 +9,7 @@ import frappe
 from frappe import _, bold
 from frappe.model.document import Document
 from frappe.query_builder import Case
-from frappe.query_builder.functions import Coalesce, GroupConcat, Locate, Max, Replace, Sum
+from frappe.query_builder.functions import Coalesce, GroupConcat, Locate, Lower, Max, Replace, Sum
 from frappe.utils import cint, floor, flt, get_link_to_form
 from frappe.utils.nestedset import get_descendants_of
 
@@ -1301,7 +1301,11 @@ def get_pending_work_orders(
 			& (wo.company == filters.get("company"))
 			& (wo.name.like(f"%{txt}%"))
 		)
-		.orderby(Case().when(Locate(txt, wo.name) > 0, Locate(txt, wo.name)).else_(99999))
+		.orderby(
+			Case()
+			.when(Locate(Lower(txt), Lower(wo.name)) > 0, Locate(Lower(txt), Lower(wo.name)))
+			.else_(99999)
+		)
 		.orderby(wo.name)
 		.limit(cint(page_length))
 		.offset(start)