diff --git a/bayer/views.py b/bayer/views.py
index 47d86e8f..114053ab 100644
--- a/bayer/views.py
+++ b/bayer/views.py
@@ -2,7 +2,7 @@ import base64
 
 import requests
 from django.conf import settings as s
-from django.http import HttpResponse, HttpResponseBadRequest
+from django.http import HttpResponse, HttpResponseBadRequest, HttpResponseNotAllowed
 from django.shortcuts import redirect
 
 from bayer.models import PESCompound
@@ -36,27 +36,49 @@ def create_pes(request, package_uuid):
             try:
                 pes_data = fetch_pes(request, pes_link)
             except ValueError as e:
-                return HttpResponseBadRequest(f"Could not fetch PES data for {pes_link}")
+                return error(
+                    request,
+                    "Could not fetch PES",
+                    f"Could not fetch PES data for {pes_link}"
+                )
 
             classification = pes_data.get("classificationLevel", "")
             if "secret" == classification.lower():
 
                 if current_package.classification_level != Package.Classification.SECRET:
-                    return HttpResponseBadRequest("Cannot create PESs for non-secret packages.")
+                    return error(
+                        request,
+                        "Classification Mismatch!",
+                        "Cannot create secret PESs in non-secret packages."
+                    )
 
                 data_pools = pes_data.get("dataPools")
                 if data_pools:
-                    if s.DATA_POOL_MAPPING[current_package.data_pool.name] not in data_pools:
-                        return HttpResponseBadRequest(
-                            f"PES data pool {s.DATA_POOL_MAPPING[current_package.data_pool.name]} not found in PES data")
+                    if (current_package.data_pool.name not in s.DATA_POOL_MAPPING
+                            or s.DATA_POOL_MAPPING[current_package.data_pool.name] not in data_pools):
+
+                        if current_package.data_pool.name not in s.DATA_POOL_MAPPING:
+                            detail = f"Data pool {current_package.data_pool.name} not found in Mapping."
+                        else:
+                            detail = f"PES data pool {s.DATA_POOL_MAPPING[current_package.data_pool.name]} not found in PES data"
+
+                        return error(
+                            request,
+                            "Invalid PES data",
+                            detail
+                        )
 
             pes = PESCompound.create(current_package, pes_data, compound_name, compound_description)
 
             return redirect(pes.url)
         else:
-            return HttpResponseBadRequest("Please provide a PES link.")
+            return error(
+                request,
+                "No PES link received",
+                "Please provide a PES link."
+            )
     else:
-        pass
+        return HttpResponseNotAllowed(["POST"])
 
 
 @package_permission_required()
@@ -82,23 +104,45 @@ def create_pes_node(request, package_uuid, pathway_uuid):
             try:
                 pes_data = fetch_pes(request, pes_link)
             except ValueError as e:
-                return HttpResponseBadRequest(f"Could not fetch PES data for {pes_link}")
+                return error(
+                    request,
+                    "Could not fetch PES",
+                    f"Could not fetch PES data for {pes_link}"
+                )
 
             classification = pes_data.get("classificationLevel", "")
             if "secret" == classification.lower():
 
                 if current_package.classification_level != Package.Classification.SECRET:
-                    return HttpResponseBadRequest("Cannot create PESs for non-secret packages.")
+                    return error(
+                        request,
+                        "Classification Mismatch!",
+                        "Cannot create secret PESs in non-secret packages."
+                    )
 
                 data_pools = pes_data.get("dataPools")
                 if data_pools:
-                    if s.DATA_POOL_MAPPING[current_package.data_pool.name] not in data_pools:
-                        return HttpResponseBadRequest(
-                            f"PES data pool {s.DATA_POOL_MAPPING[current_package.data_pool.name]} not found in PES data")
+                    if (current_package.data_pool.name not in s.DATA_POOL_MAPPING
+                            or s.DATA_POOL_MAPPING[current_package.data_pool.name] not in data_pools):
+
+                        if current_package.data_pool.name not in s.DATA_POOL_MAPPING:
+                            detail = f"Data pool {current_package.data_pool.name} not found in Mapping."
+                        else:
+                            detail = f"PES data pool {s.DATA_POOL_MAPPING[current_package.data_pool.name]} not found in PES data"
+
+                        return error(
+                            request,
+                            "Invalid PES data",
+                            detail
+                        )
 
             pes = PESCompound.create(current_package, pes_data, compound_name, compound_description)
 
-            node_qs = Node.objects.filter(pathway=current_pathway, default_node_label=pes.default_structure)
+            node_qs = Node.objects.filter(
+                pathway=current_pathway,
+                default_node_label=pes.default_structure
+            )
+
             if node_qs.exists():
                 return redirect(current_pathway.url)
 
@@ -116,9 +160,13 @@ def create_pes_node(request, package_uuid, pathway_uuid):
             return redirect(current_pathway.url)
 
         else:
-            return HttpResponseBadRequest("Please provide a PES link.")
+            return error(
+                request,
+                "No PES link received",
+                "Please provide a PES link."
+            )
     else:
-        pass
+        return HttpResponseNotAllowed(["POST"])
 
 
 def fetch_pes(request, pes_url) -> dict: