Just to clarify, I have been using gramps for 3 years and have a family tree with ~6000 people, with no problems. I am using the Relationships (combined) view when adding to my family tree and it is great.
I wanted to add a small tree just for a side research and it was with this empty tree that I saw a problem. I tried to open the Relationships view to add the first person from there and it caused the error. I used the People view to create the first person and after that the Relationships view opens with no error.
I recreated the probem with another new tree.
0251: ERROR: grampsapp.py: line 157: Unhandled exception
Traceback (most recent call last):
File “C:\Program Files\GrampsAIO64-5.1.2\gramps\gui\viewmanager.py”, line 871, in view_changed
File “C:\Program Files\GrampsAIO64-5.1.2\gramps\gui\viewmanager.py”, line 885, in __change_page
File “C:\Users\asus\AppData\Roaming\gramps\gramps51\plugins\CombinedView\navigationview.py”, line 175, in set_active
File “C:\Users\asus\AppData\Roaming\gramps\gramps51\plugins\CombinedView\navigationview.py”, line 450, in update_mru_menu
nav_type = self.navigation_type()
File “C:\Users\asus\AppData\Roaming\gramps\gramps51\plugins\CombinedView\combinedview.py”, line 170, in navigation_type
IndexError: string index out of range
Python: 3.6.4 (default, Jan 23 2018, 13:17:37) …
BSDDB: 6.1.0 (6, 0, 30)
sqlite: 3.21.0 (2.6.0)