diff --git a/owrx/form/input/__init__.py b/owrx/form/input/__init__.py
index 840985a..a0bacfb 100644
--- a/owrx/form/input/__init__.py
+++ b/owrx/form/input/__init__.py
@@ -90,10 +90,12 @@ class Input(ABC):
         return self.bootstrap_decorate(self.render_input_group(self.converter.convert_to_form(value), error))
 
     def parse(self, data):
-        value = self.converter.convert_from_form(data[self.id][0])
-        if self.validator is not None:
-            self.validator.validate(self.id, value)
-        return {self.id: value} if self.id in data else {}
+        if self.id in data:
+            value = self.converter.convert_from_form(data[self.id][0])
+            if self.validator is not None:
+                self.validator.validate(self.id, value)
+            return {self.id: value}
+        return {}
 
     def getLabel(self):
         return self.label
diff --git a/owrx/form/section.py b/owrx/form/section.py
index 3c53cf2..1eb9b9e 100644
--- a/owrx/form/section.py
+++ b/owrx/form/section.py
@@ -103,8 +103,8 @@ class OptionalSection(Section):
 
     def render(self, data, errors):
         indexed_inputs = {input.id: input for input in self.inputs}
-        visible_keys = set(self.mandatory + [k for k in self.optional if k in data])
-        optional_keys = set(k for k in self.optional if k not in data)
+        visible_keys = set(self.mandatory + [k for k in self.optional if k in data or k in errors])
+        optional_keys = set(k for k in self.optional if k not in data and k not in errors)
         self.inputs = [input for k, input in indexed_inputs.items() if k in visible_keys]
         for input in self.inputs:
             if self._is_optional(input):
@@ -117,8 +117,6 @@ class OptionalSection(Section):
 
     def parse(self, data):
         data, errors = super().parse(data)
-        # filter out errors for optional fields
-        errors = [e for e in errors if e.getKey() not in self.optional or e.getKey() in data]
         # remove optional keys if they have been removed from the form by setting them to None
         for k in self.optional:
             if k not in data: