diff --git a/backend/application.py b/backend/application.py
index 8614dd026..74bc47a3a 100644
--- a/backend/application.py
+++ b/backend/application.py
@@ -100,6 +100,10 @@ def get(self):
 
             try:
                 dataset_version = db.get_dataset_version(dataset, version)
+                if dataset_version is None:
+                    self.send_error(status_code=404)
+                    return
+
 
                 if dataset_version.available_from > datetime.now():
                     # If it's not available yet, only return if user is admin.
@@ -163,6 +167,9 @@ def get(self, dataset, version=None):
         future_version = False
 
         version = db.get_dataset_version(dataset, version)
+        if version is None:
+            self.send_error(status_code=404)
+            return
 
         if version.available_from > datetime.now():
             future_version = True
@@ -216,6 +223,10 @@ class GenerateTemporaryLink(handlers.AuthorizedHandler):
     def post(self, dataset, version=None):
         user = self.current_user
         dataset_version = db.get_dataset_version(dataset, version)
+        if dataset_version is None:
+            self.send_error(status_code=404)
+            return
+
         lh = db.Linkhash.create(
                 user            = user,
                 dataset_version = dataset_version,
@@ -240,6 +251,10 @@ def post(self, dataset, version=None):
 class DatasetFiles(handlers.AuthorizedHandler):
     def get(self, dataset, version=None):
         dataset_version = db.get_dataset_version(dataset, version)
+        if dataset_version is None:
+            self.send_error(status_code=404)
+            return
+
         ret = []
         for f in dataset_version.files:
             d = db.build_dict_from_row(f)
diff --git a/backend/db.py b/backend/db.py
index 884f72d48..d52c8a73d 100644
--- a/backend/db.py
+++ b/backend/db.py
@@ -295,16 +295,26 @@ def get_dataset(dataset):
 
 def get_dataset_version(dataset, version=None):
     if version:
-        dataset_version = (DatasetVersion
-                            .select(DatasetVersion, Dataset)
-                            .join(Dataset)
-                            .where(DatasetVersion.version == version,
-                                   Dataset.short_name == dataset)).get()
+        try:
+            dataset_version = (DatasetVersion
+                               .select(DatasetVersion, Dataset)
+                               .join(Dataset)
+                               .where(DatasetVersion.version == version,
+                                      Dataset.short_name == dataset)).get()
+        except DatasetVersion.DoesNotExist:
+            logging.error("get_dataset_version({}, {}): ".format(dataset, version) +
+                          "cannot retrieve dataset version")
+            return
     else:
-        dataset_version = (DatasetVersionCurrent
-                            .select(DatasetVersionCurrent, Dataset)
-                            .join(Dataset)
-                            .where(Dataset.short_name == dataset)).get()
+        try:
+            dataset_version = (DatasetVersionCurrent
+                               .select(DatasetVersionCurrent, Dataset)
+                               .join(Dataset)
+                               .where(Dataset.short_name == dataset)).get()
+        except DatasetVersionCurrent.DoesNotExist:
+            logging.error("get_dataset_version({}, version=None): ".format(dataset) +
+                          "cannot retrieve dataset version")
+            return
     return dataset_version