@angus さん、本当にありがとうございます。更新したところ、すべて正常に動作しているようです。
再構築中に、画面に以下のメッセージが表示されたのを見て、お知らせすることにしました：
[DEPRECATION] Template.error_mode= is deprecated. Use Environment#error_mode= instead. Called from /var/www/discourse/plugins/discourse-custom-wizard/plugin.rb:99:in 'block in Plugin::Instance#activate!'
[DEPRECATION] Template.register_filter is deprecated. Use Environment#register_filter instead. Called from /var/www/discourse/plugins/discourse-custom-wizard/plugin.rb:106:in 'block in Plugin::Instance#activate!'
I, [2026-07-22T09:33:52.756446 #1] INFO -- : > cd /var/www/discourse && su discourse -c 'bundle exec rake assets:precompile:build'
[assemble_ember_build] Node.js heap_size_limit is less than 2048MB. Setting --max-old-space-size=2048 and CHEAP_SOURCE_MAPS=1
[assemble_ember_build] No existing build info file found.
Fetching and extracting https://get.discourse.org/discourse-assets/2026.7.0-latest-6accc7b7/production.tar.gz...
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
0 0 0 0 0 0 0 0 --:--:-- --:--:-- --:--:-- 0
0 0 0 0 0 0 0 0 --:--:-- --:--:-- --:--:-- 0
100 23.3M 100 23.3M 0 0 30.9M 0 --:--:-- --:--:-- --:--:-- 184M
Prebuilt assets downloaded and extracted successfully.
[assemble_ember_build] Reusing existing core ember build. All done.
[DEPRECATION] Template.error_mode= is deprecated. Use Environment#error_mode= instead. Called from /var/www/discourse/plugins/discourse-custom-wizard/plugin.rb:99:in 'block in Plugin::Instance#activate!'
[DEPRECATION] Template.register_filter is deprecated. Use Environment#register_filter instead. Called from /var/www/discourse/plugins/discourse-custom-wizard/plugin.rb:106:in 'block in Plugin::Instance#activate!'