Add a card type with front template {{Front}}{{Back}}.
Save, click on fields, and delete the back field.
Try to rename the note type to Basic2.
Expected behavior
The note type is renamed successfully.
Actual behavior
You get an error message:
Card template <U+2068>2<U+2069> in note type '<U+2068>Basic2<U+2069>' has a problem.<br>The front side is identical to card template <U+2068>1<U+2069>.
Debug info
Anki 25.09.2 (3890e12c) (ao)
Python 3.13.5 Qt 6.9.1 PyQt 6.9.1
Platform: Windows-10-10.0.19045-SP0
===Add-ons (active)===
(add-on provided name [Add-on folder, installed at, version, is config changed])
Advanced Copy Fields ['1898445115', 2024-01-08T20:01, 'v0.4.01', '']
AnkiConnect ['2055492159', 2025-11-09T22:40, 'None', mod]
AnkiWebView Inspector ['31746032', 2023-06-27T22:26, 'None', '']
Disconnected Review-Log Cleaner ['1067771610', 2025-06-10T16:28, 'None', '']
Local Audio Server for Yomichan ['1045800357', 2023-06-19T06:57, 'None', '']
The KING of Button Add-ons ['374005964', 2025-01-28T01:26, 'None', mod]
===IDs of active AnkiWeb add-ons===
1045800357 1067771610 1898445115 2055492159 31746032 374005964
===Add-ons (inactive)===
(add-on provided name [Add-on folder, installed at, version, is config changed])
No Distractions Full Screen Fixed by Shige ['1370336700', 2024-08-26T08:08, 'None', mod]
It does not happen with the Basic note type as you described. But I can reproduce it with Basic (and reversed card). That makes sense since Basic only has one Card Type (by default), whereas Basic (and reversed card) has two.
Is that the expected behavior though? Youâve used the field-deletion to create a conflict in your card types (identical front templates). You shouldnât be able to do anything with that note type before you fix that problem.