diff --git a/module/Olcs/src/Controller/Messages/AbstractConversationMessagesController.php b/module/Olcs/src/Controller/Messages/AbstractConversationMessagesController.php
index 60f8fa8152..86ff22ec0f 100644
--- a/module/Olcs/src/Controller/Messages/AbstractConversationMessagesController.php
+++ b/module/Olcs/src/Controller/Messages/AbstractConversationMessagesController.php
@@ -113,6 +113,7 @@ protected function parseReply(Form $form)
         $form->get('id')->setValue($this->params()->fromRoute('conversation'));
 
         if (!$form->isValid()) {
+            $this->placeholder()->setPlaceholder('open-reply', true);
             return parent::indexAction();
         }
 
diff --git a/module/Olcs/src/Form/Model/Fieldset/LicenceMessageReply.php b/module/Olcs/src/Form/Model/Fieldset/LicenceMessageReply.php
index fe4a8e613c..c7f8862492 100644
--- a/module/Olcs/src/Form/Model/Fieldset/LicenceMessageReply.php
+++ b/module/Olcs/src/Form/Model/Fieldset/LicenceMessageReply.php
@@ -16,7 +16,10 @@ class LicenceMessageReply
      *     "class": "extra-long",
      *     "maxlength": 1000
      * })
-     * @Form\Options({"label": "You can enter up to 1000 characters"})
+     * @Form\Options({
+     *     "label": "You can enter up to 1000 characters",
+     *     "error-message": "Value is required and must be between 5 and 1000 characters."
+     * })
      * @Form\Required(true)
      * @Form\Type(\Laminas\Form\Element\Textarea::class)
      * @Form\Filter(\Laminas\Filter\StringTrim::class)
diff --git a/module/Olcs/view/pages/conversation/messages.phtml b/module/Olcs/view/pages/conversation/messages.phtml
index 061746c357..e0d2027c13 100644
--- a/module/Olcs/view/pages/conversation/messages.phtml
+++ b/module/Olcs/view/pages/conversation/messages.phtml
@@ -14,7 +14,7 @@
 
 
 <?php if ($this->placeholder('can-reply')->getValue()): ?>
-  <details class="govuk-details" data-module="govuk-details">
+  <details class="govuk-details" data-module="govuk-details"<?php if ($this->placeholder('open-reply')->getValue()): ?> open<?php endif; ?>>
     <summary class="govuk-details__summary" aria-controls="details-content-operating-centre">
         <span class="govuk-details__summary-text">
             Send a reply