(IDCS4Win) Strange and befuddling asserts when loading a document

Question

I am getting two strange and befuddling asserts when I am loading/manipulating a particular CS4 document.  This first one comes up once or twice when reading the document:
XferReference of invalid UID(30213) detected while reading.  Has the UID been deleted, or is it uninitialized?
I receive the second assert literally dozens of times while loading the document:
UIDCheckStream has detected an invalid reference.  It is safe to continue.
Does anyone have information on what these asserts are trying to tell me?
I am assuming that what they are telling me is that I have empty or corrupt UIDs in the document database.  Is there any way to fix these problems?
TIA,
John

Answer 1

The first assert means that some object points to a different object while the latter has been deleted.
For example, there is a page item, you removed a color and the color is still in use by the page item's stroke. Class names are for illustration purpose only, could be anything else.
The debug build iterates the whole document database to find such dangling UIDs. It opens every persistent interface and streams it thru a special PMStream to verify the existence of touched UIDs. The stream itself issues that assert, while it is called from within the ReadWrite method of the interface in question.
To solve the problem you have to find out which object is holding that reference, and guess from that the class of the deleted object (e.g. the color), because that class is not available any more for deleted objects. The only thing sure is that the deleted object is not owned / parented by the other one, otherwise the assert would be about XferObject.
How woudl you find the referring class? On a Mac, examine the stack backtrace to see wich ReadWrite is active. On Windows you probably won't have anything readable on the stack. Maybe you can export to IDML, unzip the package and use text search? Of course that assumes your reference is thru something scriptable. Otherwise IDML might at least be a way to repair the document ...
Then you have to find out the way the object was deleted, how that delete command notifies and how you can handle such references - e.g. substitute with a different color, or just clear the reference.
The way to do this depends on object type - color consumers have to register with a weird reference handling service that I still haven't fully understood, page items notify globally via PageItemUtils / kDocBoss subject, others go thru responders, and so forth.
Dirk