This is in GP 2010... it does not occur in GP2015
The error was caused by trying to eConnect a SOP document with an item number that contained a forward slant (/)
We tried troubleshooting with my usual method:
Wrap the data in a CDATA, so it would look like this: <![CDATA[MYITEM/ISBAD]]>
That didn't work
Then we tried using the PRE procedure to encode it and decode it when we got to SQL. (Our PRE and POST primer is here)
I did not solve this, except to tell the customer that they'll need to use the Item Number Changer in the Professional Tools Services Library.
But... there is some discussion of what I tried below.