Index: src/routes/admin-sites.js
===================================================================
--- src/routes/admin-sites.js	(revision ccaa5301c212451f2e6b7c28c49282055278e961)
+++ src/routes/admin-sites.js	(revision 5462bab0a30abfb9338812cb154a11cebda17b67)
@@ -211,4 +211,5 @@
     platforms: listPlatforms(),
     parsedLinks: [],
+    apAliases: '',
     error: null,
   });
Index: src/views/pages/admin-site-edit.ejs
===================================================================
--- src/views/pages/admin-site-edit.ejs	(revision ccaa5301c212451f2e6b7c28c49282055278e961)
+++ src/views/pages/admin-site-edit.ejs	(revision 5462bab0a30abfb9338812cb154a11cebda17b67)
@@ -217,5 +217,8 @@
       <p class="form-hint"><%= t('asite.aliases_hint') %></p>
       <label>
-        <textarea name="ap_aliases" rows="3" placeholder="@oud@mastodon.social&#10;https://andere-klonkt.example/ap/users/naam"><%= apAliases %></textarea>
+<%# typeof-guard on purpose: during a deploy an old route can render this new
+    template for one request (view cache fills on first hit). A missing local
+    must degrade to an empty field, not take the whole page down with a 500. %>
+        <textarea name="ap_aliases" rows="3" placeholder="@oud@mastodon.social&#10;https://andere-klonkt.example/ap/users/naam"><%= typeof apAliases !== 'undefined' ? apAliases : '' %></textarea>
       </label>
     </fieldset>