diff --git a/src/applications/maniphest/auxiliaryfield/ManiphestAuxiliaryFieldDefaultSpecification.php b/src/applications/maniphest/auxiliaryfield/ManiphestAuxiliaryFieldDefaultSpecification.php
index 8338c6dc6a..980b87967b 100644
--- a/src/applications/maniphest/auxiliaryfield/ManiphestAuxiliaryFieldDefaultSpecification.php
+++ b/src/applications/maniphest/auxiliaryfield/ManiphestAuxiliaryFieldDefaultSpecification.php
@@ -100,6 +100,9 @@ class ManiphestAuxiliaryFieldDefaultSpecification
       case self::TYPE_DATE:
         $control = new AphrontFormDateControl();
         $control->setUser($this->getUser());
+        if (!$this->isRequired()) {
+          $control->setAllowNull(true);
+        }
         break;
       case self::TYPE_REMARKUP:
         $control = new PhabricatorRemarkupControl();
@@ -132,7 +135,9 @@ class ManiphestAuxiliaryFieldDefaultSpecification
           (bool)$this->getValue());
         break;
       case self::TYPE_DATE:
-        $control->setValue($this->getValue());
+        if ($this->getValue() > 0) {
+          $control->setValue($this->getValue());
+        }
         $control->setName('auxiliary_date_'.$this->getAuxiliaryKey());
         break;
       case self::TYPE_USER:
@@ -201,7 +206,7 @@ class ManiphestAuxiliaryFieldDefaultSpecification
       case self::TYPE_USERS:
         return json_encode($this->getValue());
       default:
-        return $this->getValue();
+        return (int)$this->getValue();
     }
   }
 
@@ -216,9 +221,7 @@ class ManiphestAuxiliaryFieldDefaultSpecification
         break;
       case self::TYPE_DATE:
         $value = (int)$value;
-        if ($value <= 0) {
-          return $this->setDefaultValue($value);
-        }
+        $this->setDefaultValue($value);
         break;
       default:
         break;
@@ -243,7 +246,7 @@ class ManiphestAuxiliaryFieldDefaultSpecification
       case self::TYPE_SELECT:
         return true;
       case self::TYPE_DATE:
-        if ((int)$this->getValue() <= 0) {
+        if ((int)$this->getValue() <= 0 && $this->isRequired()) {
           throw new ManiphestAuxiliaryFieldValidationException(
             pht(
               '%s must be a valid date.',
@@ -367,7 +370,7 @@ class ManiphestAuxiliaryFieldDefaultSpecification
         // fields normally, users can change the type of an existing field and
         // leave us with uninterpretable data in old transactions.
         if ((int)$new <= 0) {
-          $new_display = "(invalid epoch timestamp: {$new})";
+          $new_display = "none";
         } else {
           $new_display = phabricator_datetime($new, $this->getUser());
         }
@@ -375,7 +378,7 @@ class ManiphestAuxiliaryFieldDefaultSpecification
           $desc = "set field '{$label}' to '{$new_display}'";
         } else {
           if ((int)$old <= 0) {
-            $old_display = "(invalid epoch timestamp: {$old})";
+            $old_display = "none";
           } else {
             $old_display = phabricator_datetime($old, $this->getUser());
           }
diff --git a/src/applications/maniphest/controller/ManiphestTaskEditController.php b/src/applications/maniphest/controller/ManiphestTaskEditController.php
index cba05b3ec6..f578e37e0b 100644
--- a/src/applications/maniphest/controller/ManiphestTaskEditController.php
+++ b/src/applications/maniphest/controller/ManiphestTaskEditController.php
@@ -123,8 +123,15 @@ final class ManiphestTaskEditController extends ManiphestController {
         $errors[] = pht('Title is required.');
       }
 
-      foreach ($aux_fields as $aux_field) {
+      foreach ($aux_fields as $aux_arr_key => $aux_field) {
         $aux_field->setValueFromRequest($request);
+        $aux_key = $aux_field->getAuxiliaryKey();
+        $aux_old_value = $task->getAuxiliaryAttribute($aux_key);
+
+        if ((int)$aux_old_value === $aux_field->getValueForStorage()) {
+          unset($aux_fields[$aux_arr_key]);
+          continue;
+        }
 
         if ($aux_field->isRequired() && !$aux_field->getValue()) {
           $errors[] = pht('%s is required.', $aux_field->getLabel());
diff --git a/webroot/rsrc/css/phui/phui-form.css b/webroot/rsrc/css/phui/phui-form.css
index 09139df1ad..92bdacc40e 100644
--- a/webroot/rsrc/css/phui/phui-form.css
+++ b/webroot/rsrc/css/phui/phui-form.css
@@ -129,6 +129,7 @@ textarea::-webkit-input-placeholder {
 }
 
 
-select[disabled="disabled"] {
+select[disabled="disabled"],
+input[disabled="disabled"] {
   opacity: 0.5;
 }