Fixes #2471

packages/strapi-plugin-content-manager/admin/src/components/Inputs/index.js

@@ -121,6 +121,29 @@ function Inputs({ autoFocus, keys, layout, name, onBlur }) {
     step = '1';
   }
 
+  const options = get(attribute, 'enum', []).map(v => {
+    return (
+      <option key={v} value={v}>
+        {v}
+      </option>
+    );
+  });
+
+  const isRequired = get(validations, ['required'], false);
+  const enumOptions = [
+    <FormattedMessage
+      id="components.InputSelect.option.placeholder"
+      key="__enum_option_null"
+    >
+      {msg => (
+        <option disabled={isRequired} hidden={isRequired} value="">
+          {msg}
+        </option>
+      )}
+    </FormattedMessage>,
+    ...options,
+  ];
+
   return (
     <FormattedMessage id={errorId}>
       {error => {
@@ -147,7 +170,7 @@ function Inputs({ autoFocus, keys, layout, name, onBlur }) {
             name={keys}
             onBlur={onBlur}
             onChange={onChange}
-            options={get(attribute, 'enum', [])}
+            options={enumOptions}
             step={step}
             type={getInputType(type)}
             validations={validations}

packages/strapi-plugin-content-manager/admin/src/containers/EditViewDataManagerProvider/index.js

@@ -196,7 +196,8 @@ const EditViewDataManagerProvider = ({
       inputValue = null;
     }
 
-    if (type === 'biginteger' && value === '') {
+    // Allow to reset enum
+    if (type === 'select-one' && value === '') {
       inputValue = null;
     }
 

packages/strapi-plugin-content-type-builder/admin/src/containers/FormModal/utils/forms.js

@@ -42,7 +42,11 @@ yup.addMethod(yup.string, 'unique', function(
 
 yup.addMethod(yup.array, 'hasNotEmptyValues', function(message) {
   return this.test('hasNotEmptyValues', message, function(array) {
-    return !array.some(value => isEmpty(value));
+    return (
+      !array.some(value => {
+        return isEmpty(value);
+      }) && array.every(value => ENUM_REGEX.test(value))
+    );
   });
 });