diff --git a/InvenTree/InvenTree/models.py b/InvenTree/InvenTree/models.py
index 4e7ed89e63..52c5384b63 100644
--- a/InvenTree/InvenTree/models.py
+++ b/InvenTree/InvenTree/models.py
@@ -107,7 +107,10 @@ class InvenTreeAttachment(models.Model):
         return "attachments"
 
     def __str__(self):
-        return os.path.basename(self.attachment.name)
+        if self.attachment is not None:
+            return os.path.basename(self.attachment.name)
+        else:
+            return str(self.link)
 
     attachment = models.FileField(upload_to=rename_attachment, verbose_name=_('Attachment'),
                                   help_text=_('Select file to attach'),
@@ -134,7 +137,10 @@ class InvenTreeAttachment(models.Model):
 
     @property
     def basename(self):
-        return os.path.basename(self.attachment.name)
+        if self.attachment:
+            return os.path.basename(self.attachment.name)
+        else:
+            return None
 
     @basename.setter
     def basename(self, fn):
diff --git a/InvenTree/InvenTree/serializers.py b/InvenTree/InvenTree/serializers.py
index 90cc857cdd..c236bad603 100644
--- a/InvenTree/InvenTree/serializers.py
+++ b/InvenTree/InvenTree/serializers.py
@@ -239,22 +239,6 @@ class InvenTreeModelSerializer(serializers.ModelSerializer):
         return data
 
 
-class InvenTreeAttachmentSerializer(InvenTreeModelSerializer):
-    """
-    Special case of an InvenTreeModelSerializer, which handles an "attachment" model.
-
-    The only real addition here is that we support "renaming" of the attachment file.
-    """
-
-    # The 'filename' field must be present in the serializer
-    filename = serializers.CharField(
-        label=_('Filename'),
-        required=False,
-        source='basename',
-        allow_blank=False,
-    )
-
-
 class InvenTreeAttachmentSerializerField(serializers.FileField):
     """
     Override the DRF native FileField serializer,
@@ -284,6 +268,46 @@ class InvenTreeAttachmentSerializerField(serializers.FileField):
         return os.path.join(str(settings.MEDIA_URL), str(value))
 
 
+class InvenTreeAttachmentSerializer(InvenTreeModelSerializer):
+    """
+    Special case of an InvenTreeModelSerializer, which handles an "attachment" model.
+
+    The only real addition here is that we support "renaming" of the attachment file.
+    """
+
+    def validate(self, data):
+        """
+        Validation for an attachment. Either a file or external link must be provided
+        """
+
+        data = super().validate(data)
+
+        attachment = data.get('attachment', None)
+        link = data.get('link', None)
+
+        if not attachment and not link:
+            raise ValidationError({
+                'attachment': _('Missing file'),
+                'link': _('Missing external link'),
+            })
+
+        return data
+
+    attachment = InvenTreeAttachmentSerializerField(
+        required=False,
+        allow_null=False,
+    )
+
+    # The 'filename' field must be present in the serializer
+    filename = serializers.CharField(
+        label=_('Filename'),
+        required=False,
+        source='basename',
+        allow_blank=False,
+    )
+
+
+
 class InvenTreeImageSerializerField(serializers.ImageField):
     """
     Custom image serializer.
diff --git a/InvenTree/build/serializers.py b/InvenTree/build/serializers.py
index 12f57f980a..338e4a38b3 100644
--- a/InvenTree/build/serializers.py
+++ b/InvenTree/build/serializers.py
@@ -516,8 +516,6 @@ class BuildAttachmentSerializer(InvenTreeAttachmentSerializer):
     Serializer for a BuildAttachment
     """
 
-    attachment = InvenTreeAttachmentSerializerField(required=True)
-
     class Meta:
         model = BuildOrderAttachment
 
diff --git a/InvenTree/order/serializers.py b/InvenTree/order/serializers.py
index a3674afb59..c1356d78c9 100644
--- a/InvenTree/order/serializers.py
+++ b/InvenTree/order/serializers.py
@@ -377,8 +377,6 @@ class POAttachmentSerializer(InvenTreeAttachmentSerializer):
     Serializers for the PurchaseOrderAttachment model
     """
 
-    attachment = InvenTreeAttachmentSerializerField(required=True)
-
     class Meta:
         model = PurchaseOrderAttachment
 
@@ -598,8 +596,6 @@ class SOAttachmentSerializer(InvenTreeAttachmentSerializer):
     Serializers for the SalesOrderAttachment model
     """
 
-    attachment = InvenTreeAttachmentSerializerField(required=True)
-
     class Meta:
         model = SalesOrderAttachment
 
diff --git a/InvenTree/part/serializers.py b/InvenTree/part/serializers.py
index 189665fb32..1be81c16ba 100644
--- a/InvenTree/part/serializers.py
+++ b/InvenTree/part/serializers.py
@@ -75,8 +75,6 @@ class PartAttachmentSerializer(InvenTreeAttachmentSerializer):
     Serializer for the PartAttachment class
     """
 
-    attachment = InvenTreeAttachmentSerializerField(required=True)
-
     class Meta:
         model = PartAttachment
 
diff --git a/InvenTree/stock/serializers.py b/InvenTree/stock/serializers.py
index 39ebd13acb..c74d674275 100644
--- a/InvenTree/stock/serializers.py
+++ b/InvenTree/stock/serializers.py
@@ -420,8 +420,6 @@ class StockItemAttachmentSerializer(InvenTree.serializers.InvenTreeAttachmentSer
 
     user_detail = InvenTree.serializers.UserSerializerBrief(source='user', read_only=True)
 
-    attachment = InvenTree.serializers.InvenTreeAttachmentSerializerField(required=True)
-
     # TODO: Record the uploading user when creating or updating an attachment!
 
     class Meta: