Error <LIST>%SerializeObject+5

Reading the doc (https://docs.intersystems.com/irislatest/csp/docbook/DocBook.UI.Page.cls...) looks like your response has a problem with a list property but I can't say more with just a screenshot.

Maybe you're using literal properties for list operation. It causes the list error.

In general, a <LIST> error indicates a malformed $list value.

USER>set bad = "something wrong"   

USER>write $li(bad,1)

WRITE $LI(bad,1)
^
<LIST>
USER>set good = $listbuild("something right")

USER>write $li(good,1)
something right

In %SerializeObject, this typically is caused by an expectation that a value is a valid list but it is not. In a more complex class that extends %SerialObject, one that contains at least one property whose type class is a swizzlable (persistent, serial, stream), $list(value, n) is used to extract the object value (id or serial value) from a value that is expected to be an OID. While OID's an be more complex, the typical OID format is $list(<serialized object value>, <most specific type class>). <serialized object value> can be a simple ID and <most specific type class> (MSTC) is the class of which the object is an instance but not an instance of any subclass of MSTC.

That isn't the only possibility but it is the most likely. I can't be more specific without seeing the full class definition.

-Dan