diff --git a/modules/salesforce_mapping/src/SalesforceMappingFieldPluginBase.php b/modules/salesforce_mapping/src/SalesforceMappingFieldPluginBase.php
index ed53876e..51f77644 100644
--- a/modules/salesforce_mapping/src/SalesforceMappingFieldPluginBase.php
+++ b/modules/salesforce_mapping/src/SalesforceMappingFieldPluginBase.php
@@ -238,6 +238,13 @@ abstract class SalesforceMappingFieldPluginBase extends PluginBase implements Sa
           $value = (string) (new SFID($value));
         }
         break;
+
+      case 'textarea':
+        // If value is array, implode the values for textarea.
+        if (is_array($value)) {
+          $value = implode(', ', $value);
+        }
+        break;
     }
 
     if ($field_definition['length'] > 0 && strlen($value) > $field_definition['length']) {