#1552 SVN 1442 - ERROR 20 when merging family

[Meliza Amity]

I merged 2 children in 2 families. (I5324 and I9351)
I then merged the fathers. (I9352 and I23929)
After that I merged the 2 families (F3919 and F6717) and got errors.

GEDCOM record successfully deleted.
Updating linked record I23929
ERROR 20: Invalid GEDCOM 5.5 format. Updating linked record I5324
Updating linked record F6717
ERROR 20: Invalid GEDCOM 5.5 format. Adding HUSB from F3919
Adding CHIL from F3919

Only after this I approved all the changes.

[Meliza Amity]

Logged In: YES
user_id=959928
Originator: YES

I tried to undo ALL the above changes.
only some were undone - others remained pending.
I had to be deleted one by one.