diff --git a/core/server/api/v2/utils/serializers/output/utils/extra-attrs.js b/core/server/api/v2/utils/serializers/output/utils/extra-attrs.js
index cfd5ad08ae..8f6fb7c1bf 100644
--- a/core/server/api/v2/utils/serializers/output/utils/extra-attrs.js
+++ b/core/server/api/v2/utils/serializers/output/utils/extra-attrs.js
@@ -5,7 +5,10 @@ module.exports.forPost = (frame, model, attrs) => {
         (frame.options.columns.includes('excerpt') && frame.options.formats && frame.options.formats.includes('plaintext'))) {
         if (_.isEmpty(attrs.custom_excerpt)) {
             const plaintext = model.get('plaintext');
-            attrs.excerpt = plaintext.substring(0, 500);
+
+            if (plaintext) {
+                attrs.excerpt = plaintext.substring(0, 500);
+            }
         } else {
             attrs.excerpt = attrs.custom_excerpt;
         }