Crash log is too long, so I put it on Dropbox here.

Essentially, attempting to rename any character other than the currently-active one causes this crash. From the looks of the crash log, it seems to be some kind of infinite loop.

Thanks for the report. This bug should be fixed now

Still crashing when renaming a non-active character, unfortunately. Seems to be the same crash, but different line numbers. Uploading crash log to Dropbox here.

I didn't realize you were renaming the character via map tag and not the GUI.
The bug should now be fixed

I was? I just clicked the "pencil" button in the same GUI where I swap between them, and where I change their colour. I have no idea how a map tag would even become involved. Maybe a mod conflict on my side?

Just to mention: I'm still crashing, but it's a NEW crash this time :) And a finite one, it seems. Listing below as I see it:

Error while running event multiple-characters::on_gui_confirmed (ID 166)
The mod Multiple Characters (0.4.6) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event multiple-characters::on_chart_tag_modified (ID 164)
__multiple-characters__/control.lua:482: bad argument #3 of 3 to '__index' (string expected, got nil)
stack traceback:
[C]: in function '__index'
__multiple-characters__/control.lua:482: in function <__multiple-characters__/control.lua:472>
stack traceback:
[C]: in function '__newindex'
__multiple-characters__/control.lua:407: in function 'rename_character'
__multiple-characters__/gui.lua:390: in function <__multiple-characters__/gui.lua:387>

Incidentally, I still VERY much love the mod, even if I have to be careful how I rename characters.

I could only reproduce the previous crash when renaming the map tag.
This new crash should (hopefully) now be fixed :D
Glad you're enjoying the mod!

Yay! :) I can confirm that the mod no longer crashes when renaming a non-active character. I even put a planet icon in the name. No idea what's causing the map tag to try and rename itself. For the record - my name on the map doesn't change. It keeps using my Steam Name, no matter what I call the character in the Multiple Characters menu. But I do see the correct name in that menu, which is realistically all that matters. I named all my characters for the planet they manage, so I don't have to guess by the screenshot thumbnail.

So far, all the crashes seem to be gone.