Back up doesn't start

Comienza con apps/backup/lib/Cron/Backup.php, especialmente con la línea 126 de runDifferentialBackup, y revisa cómo el trabajo programado llega a ese punto. Reproduce el fallo con Nextcloud 24.0.5 en Yunohost y Nextcloud 24.0.2 en Ubuntu, usando almacenamiento externo. Se considera terminado cuando el trabajo de backup se inicia y finaliza sin este error registrado.

I have followed the documentation on how to set up back up, but it doesn't start.
I am using Nextcloud 24.0.5 via Yunohost and trying to make a back up and send it to external storage, Nextcloud 24.0.2 on Ubuntu.

This is the error from the log:
{"reqId":"RlUrBqqTpTjOQxbbrja4","level":3,"time":"2022-10-18T08:00:04+00:00","remoteAddr":"","user":"--","app":"backup","method":"","url":"--","message":"error while running differential backup - [{\"file\":\"\\/var\\/www\\/nextcloud\\/apps\\/backup\\/lib\\/Cron\\/Backup.php\",\"line\":126,\"function\":\"runDifferentialBackup\",\"class\":\"OCA\\\\Backup\\\\Cron\\\\Backup\",\"object\":{},\"type\":\"->\",\"args\":[]},{\"file\":\"\\/var\\/www\\/nextcloud\\/apps\\/backup\\/lib\\/Cron\\/Backup.php\",\"line\":115,\"function\":\"runBackup\",\"class\":\"OCA\\\\Backup\\\\Cron\\\\Backup\",\"object\":{},\"type\":\"->\",\"args\":[1666080004]},{\"file\":\"\\/var\\/www\\/nextcloud\\/apps\\/backup\\/lib\\/Cron\\/Backup.php\",\"line\":97,\"function\":\"manage\",\"class\":\"OCA\\\\Backup\\\\Cron\\\\Backup\",\"object\":{},\"type\":\"->\",\"args\":[]},{\"file\":\"\\/var\\/www\\/nextcloud\\/lib\\/private\\/BackgroundJob\\/Job.php\",\"line\":54,\"function\":\"run\",\"class\":\"OCA\\\\Backup\\\\Cron\\\\Backup\",\"object\":{},\"type\":\"->\",\"args\":[null]},{\"file\":\"\\/var\\/www\\/nextcloud\\/lib\\/private\\/BackgroundJob\\/TimedJob.php\",\"line\":60,\"function\":\"execute\",\"class\":\"OC\\\\BackgroundJob\\\\Job\",\"object\":{},\"type\":\"->\",\"args\":[{},{}]},{\"file\":\"\\/var\\/www\\/nextcloud\\/cron.php\",\"line\":151,\"function\":\"execute\",\"class\":\"OC\\\\BackgroundJob\\\\TimedJob\",\"object\":{},\"type\":\"->\",\"args\":[{},{}]}]","userAgent":"--","version":"24.0.5.1","data":{"app":"backup"},"id":"634e7dce465c6"}