Multiple ajax calls returns empty span

When using an entity reference field and multiple ajax requests are triggered (by clicking more than one buttons having ajax callback). The entity reference form ends up being empty i.e doesnot show any fields. I checked the recent log entries and found the following error:
Notice: Undefined index: #prefix in Drupal\file\Element\ManagedFile::uploadAjaxCallback() (line 196 of docroot/core/modules/file/src/Element/ManagedFile.php) #0