diff --git a/epdb/views.py b/epdb/views.py
index d6e54dd2..a4db722e 100644
--- a/epdb/views.py
+++ b/epdb/views.py
@@ -1918,6 +1918,21 @@ def package_reactions(request, package_uuid):
         reaction_name = request.POST.get("reaction-name")
         reaction_description = request.POST.get("reaction-description")
         reaction_smiles = request.POST.get("reaction-smiles")
+
+        if reaction_smiles is None or reaction_smiles.strip() == "":
+            return error(
+                request,
+                "Reaction SMILES is empty / missing",
+                "No reaction SMILES provided. Please provide a SMILES for the reaction.",
+            )
+
+        if not FormatConverter.is_valid_smirks(reaction_smiles):
+            return error(
+                request,
+                "Reaction SMILES is invalid",
+                f"The provided reactions SMILES {reaction_smiles} is invalid",
+            )
+
         educts = reaction_smiles.split(">>")[0].split(".")
         products = reaction_smiles.split(">>")[1].split(".")