This bug was filed from the crash reporting server and is br-bc73da5a-1efd-479f-96c7-28e466dc8280.
1) Open new Writer document
2) Tools > Mailmerge wizard
3a) "Start with existing document" > Choose file > "Next"
3b) "Create a new document" > "Next"
If I choose "Use the current document" work correctly.
*** This bug has been marked as a duplicate of bug 105684 ***