When I use “Customize Keyboard Shortcuts” with 2.1.29 I don’t get this message. You seem to have an old version of this add-on.
If you can get to the main screen: to update all add-ons go the main window ->Tools -> Add-ons and then there’s a button “Check for Updates”. After updating all add-ons restart: Do you still have the problem?
If it persists: Read the checklist at https://anki.tenderapp.com/kb/problems/when-problems-occur Disable all other add-ons and restart. Does the problem persist?
Your info “newest update” is not saying much. If the problem persists also share this: From the main window click on Help->About. In the window that opens click the “Copy Debug Info” Button and share the copied text.
Or maybe just disable the add-on ‘Customize Keyboard Shortcuts’: