When trying to submit a Record Producer and the "sc_cat_item" page is stuck at submitting and there is a 404 (Invalid Request) error on the console. This might be due to an exception on the nodelogs, Please see the below example
2018-05-18 07:40:00 (719) Default-thread-3 D242BC9FDBCE9F00EEC724B3CA96190F txid=95747c93db02 WARNING *** WARNING *** Evaluator: java.lang.ClassCastException: com.glide.script.GlideElement cannot be cast to com.glide.script.glide_elements.GlideElementReference
Caused by error in <refname> at line 54
If you don't the see the exception other than the Service Catalog Rest API error, Please add the item to the cart and then try to submit again.
Browser, Service Portal
Change in Request Item Dictionary Data Type
Please check the Dictionary Entry for these 2 fields "Item", "Short Description", "Opened by" and "Request" fields in Requested Items (sc_req_item) table and compare it with an OOB instance.