diff --git a/CHANGELOG.md b/CHANGELOG.md
index a2019f4..8427520 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,11 @@
 ## Changelog
 
+### v0.31.5 — Fix Nextcloud-OnlyOffice callback URL + trusted_domains (2026-02-25)
+
+#### Fixed
+- **StorageUrl trailing slash**: `http://nextcloud` → `http://nextcloud/` — without trailing slash, Nextcloud's OO connector concatenates the hostname with `/apps/...` path, producing `http://nextcloudapps/...` (unresolvable hostname)
+- **trusted_domains**: OO Document Server callbacks arrive with `Host: nextcloud` header; added `nextcloud` to Nextcloud's trusted_domains so these internal callbacks are not rejected
+
 ### v0.31.4 — Fix FB container not restarting + OO mixed content (2026-02-25)
 
 #### Fixed
diff --git a/controller/internal/integrations/onlyoffice_nextcloud.go b/controller/internal/integrations/onlyoffice_nextcloud.go
index 6e2a27c..6d9445b 100644
--- a/controller/internal/integrations/onlyoffice_nextcloud.go
+++ b/controller/internal/integrations/onlyoffice_nextcloud.go
@@ -50,8 +50,15 @@ func (h *OnlyOfficeNextcloudHandler) Apply(ac *ApplyContext) error {
 			args: []string{"docker", "exec", "-u", "www-data", "nextcloud", "php", "occ", "config:app:set", "onlyoffice", "jwt_secret", "--value=" + jwtSecret},
 		},
 		{
-			// StorageUrl: tells OO Document Server where to reach Nextcloud internally for file callbacks
-			args: []string{"docker", "exec", "-u", "www-data", "nextcloud", "php", "occ", "config:app:set", "onlyoffice", "StorageUrl", "--value=http://nextcloud"},
+			// StorageUrl: tells OO Document Server where to reach Nextcloud internally for file callbacks.
+			// Trailing slash is critical — NC's OO connector does string replacement of the server URL
+			// (which ends with /) with StorageUrl. Without trailing slash, "/apps/..." merges into hostname.
+			args: []string{"docker", "exec", "-u", "www-data", "nextcloud", "php", "occ", "config:app:set", "onlyoffice", "StorageUrl", "--value=http://nextcloud/"},
+		},
+		{
+			// Add internal hostname to trusted_domains so OO Document Server callbacks
+			// (arriving with Host: nextcloud) are not rejected by Nextcloud.
+			args: []string{"docker", "exec", "-u", "www-data", "nextcloud", "php", "occ", "config:system:set", "trusted_domains", "10", "--value=nextcloud"},
 		},
 	}