This is very specific error but can happen in some scenerios. When my product name/label starts with "0" (and it does happen often when SKU is used for label as in #1940664: Allow SKU in autocomplete reference widget) and start typing "0..." this gets interpreted as empty in inline_entity_form_autocomplete and therefore MENU_ACCESS_DENIED is returned as result.

Files: 
CommentFileSizeAuthor
entityreference_title_starts_with_0.patch650 bytesphilipz

Comments

Title:When title/label start with 0 ajax error may happen when adding product referenceAutocomplete callback throws error 500 for valid string '0'
Issue summary:View changes
Status:Active» Fixed

Status:Fixed» Closed (fixed)

Automatically closed - issue fixed for 2 weeks with no activity.