@usdanskys filed a bug report last month that appears to be related to either corrupt custom display formats for Names or bad pointers to that list.
See 0013347: new person window comes up with “Preferred Name” and "“ERROR, Edit Name format in Preferences [XXXXX]” QuLogic submitted a patch PR posted 26 Aug 2024 as noted in the Bug Tracking
I think the problem is related to having a Custom Name Display Format set as the default in the [preferences] chunk of the gramps.ini but where Gramps won’t be aware anything but a placeholder the built-in formats until a Tree is loaded.
So what happens if Preferences is set to -1, the 1st custom display name format when Gramps starts with no Tree? Does it set a dummy placeholder that is NULL for the fmt_str and its name. And then when the Tree is loaded or an XML is loaded into the Gramps workspace, maybe all the custom formats are pushed down in the list?
How can we diagnose his file? Can we use SuperTool (dashboard category) script to get a raw list of the known display formats before a database is loaded, after, and after importing the .gramps XML into a new, blank tree?
The topic linked at the bottom will list the display_as for all the selected People. To do proper diagnostic, we probably need a report finding all People leveraging alternative display_as settings.
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE database PUBLIC "-//Gramps//DTD Gramps XML 1.7.1//EN"
"http://gramps-project.org/xml/1.7.1/grampsxml.dtd">
<database xmlns="http://gramps-project.org/xml/1.7.1/">
<header>
<created date="2024-08-19" version="5.2.1"/>
</header>
<name-formats>
<format number="-3" name="Given NotPatronymic Patronymic" fmt_str="given Notpatronymic patronymic" active="1"/>
<format number="-2" name="SURNAME, Given Suffix (Common)" fmt_str="SURNAME, given suffix (common)" active="1"/>
<format number="-1" name="Given SURNAME, Suffix" fmt_str="given SURNAME, suffix" active="1"/>
</name-formats>
<people>
<person handle="_fae412920c541f1ea1bde07c5cb" change="1724109313" id="I0000">
<gender>M</gender>
<name type="Birth Name" display="-2">
<first>John</first>
<surname derivation="Patrilineal">Smith</surname>
</name>
<name alt="1" type="Also Known As">
<first>Johann</first>
<surname prefix="von" derivation="Patronymic">Schmidt</surname>
</name>
</person>
</people>
</database>
Pertinent entry in the gramps.ini
[preferences]
⋮
name-format=-3
⋮
Patrice ( @PLegoux ) posted a SuperTool Script in another topic which reads the display_as values for all the Preferred and Alternative Names for a Person.