diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4d3997c..e4db1a7 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,11 +7,15 @@ the app store accepts a `-beta` suffix, but Nextcloud servers then only offer th
 beta/daily update channel, which would hide the app from most admins. The stability stage is
 instead carried by the app description, the git tag, the release, and this file.
 
-## [1.0.0-rc.5] - 2026-10-21
+## [1.0.0-rc.5] - 2026-10-22
 
 Fifth release candidate for 1.0.0; the app version is 0.9.11. A full restore of 1 TB over SFTP
 stopped after 13 hours with "Blob not in index"; the backup itself was fine.
 
+### Changed
+- README and app store description: NG Backup needs background jobs on system cron, with how to
+  set that up (issues #13, #17).
+
 ### Fixed
 - A full restore no longer stops with "Blob not in index" after a pack could not be read for a
   moment. Reading the index again then got an empty listing (from a connection the location had
diff --git a/README.md b/README.md
index db2595c..47ef3c1 100644
--- a/README.md
+++ b/README.md
@@ -33,6 +33,26 @@ Need help restoring a backup after a crash? Ensembia offers paid restore assista
 - Restores go through Nextcloud, so overwritten files keep their old content as a version and
   removed files go to the trash.
 
+## Requirements
+
+- **Background jobs on system cron.** NG Backup runs backups in steps from Nextcloud's
+  background job, so a backup only moves forward when that job runs. Choosing "Cron" under
+  **Administration settings → Basic settings → Background jobs** is not enough on its own: it
+  tells Nextcloud that the system will call it, so you also need a cron line that does. Without
+  it a backup stays at "running (db)", and so does one started with "Back up now".
+  `occ backup:run` in a terminal works without cron (it runs in the foreground).
+  - Regular server: `crontab -u www-data -e` and add
+    `*/5 * * * * php -f /var/www/nextcloud/cron.php` (your Nextcloud path).
+  - Docker (the official `nextcloud` image): on the host, `crontab -e` as root and add
+    `*/5 * * * * docker exec -u www-data <container> php -f /var/www/html/cron.php`, or add a
+    service with the same image and `entrypoint: /cron.sh` to your `docker-compose.yml`.
+  - Nextcloud All-in-One already runs cron.
+
+  After a few minutes, the Background jobs section shows that the last job ran just now. See the
+  [Nextcloud documentation on background jobs](https://docs.nextcloud.com/server/latest/admin_manual/configuration_server/background_jobs_configuration.html).
+- A storage location: S3 or compatible, SFTP, WebDAV, SMB (needs the PHP `smbclient` extension,
+  see below), FTP or a local path.
+
 ## Quick start
 
 ```
diff --git a/appinfo/info.xml b/appinfo/info.xml
index 536aa46..ba68b03 100644
--- a/appinfo/info.xml
+++ b/appinfo/info.xml
@@ -36,6 +36,7 @@ All-in-One and hosted Nextcloud.
 - One user (account, files, calendars, contacts) via user_migration.
 - The whole server onto a fresh installation (disaster recovery).
 
+NG Backup needs Nextcloud's background jobs on system cron (a real cron line, not only the setting).
 Read "Known limitations" in the README before you rely on it, and test a restore. Feedback is very
 welcome: use the "Share your experience" link on the admin page.