Problem exporting TM to TMX

Question

I have recently upgraded from Studio 2016 to 2017.
When I try to upgrade my TM, when the process is approx. 20% completed, I receive the message "There is an error in XML document (1, 1)"

The TM size is 1.3 GB.
I receive the same message, at the same stage in the process, when I try to export it to a TMX file or to re-index the translation memory.
However, the TM works perfectly when I am actually working on a project.

Two other TMs (one larger, one smaller) upgraded without any problem.
The problem occurs on both my laptop and desktop.

Paul · Accepted Answer

Thanks Diarmuid, 
 
Perhaps just to clarify part of what you have posted. The reason for searching for that text was because I used a SQLite editor to find a TU that was missing the source content altogether. I then copied target to source in the SQLite editor and this allowed me to export to TMX in Studio. 
 
I used this editor for the SQL: 
 
 http://sqlitebrowser.org/ 
 
Regards 
 
Paul

Paul · Answer

Hello Diarmuid, 
 
Have you tried repairing the TM? 
 
 appstore.sdl.com/.../ 
 
Regards 
 
Paul

Trados Studio > 1. Trados Studio

Problem exporting TM to TMX