Just thought I'd share for folks who run into it, since I got asked the question by someone else.
While exporting an object as text from version 5.0, my friend was getting:
There are errors in the text conversion (text no. 165-205 does not exist in the .stx file).
Internal error: 47-1
The object compiles fine, exports as FOB fine. But, I knew he's been working a lot between 5.0 and 6.0, as was the client. So, I opened up the 5.0 and 6.0 stx files and compared. Sure enough, "00165-00205-030-0: CaptionClassText" was added in 6.0's fin.stx. Someone had opened the object in a 6.0 version, exported it as a FOB from a 6.0 database, and stuck the 6.0 FOB into the 5.0 database.
So, mixing and matching versions, even through FOB's, isn't always as successful as one might think at first blush.
(The fix to handle doing what he needs, the object as a text file? Export it as a FOB to get it back into a 6.0 database, then export as text from there.)