Hello World 
The Basics
- Nextcloud Server version (e.g., 29.x.x):
- 30.0.8
- Operating system and version (e.g., Ubuntu 24.04):
- Ubuntu 22.04
- Web server and version (e.g, Apache 2.4.25):
- Apache2
- Reverse proxy and version _(e.g. nginx 1.27.2)
- No Proxy
- PHP version (e.g, 8.3):
- 8.3.19
- Is this the first time you’ve seen this error? (Yes / No):
- Yes
- When did this problem seem to first start?
- Upgrade to php 8.3 and fixed the cron job
- Installation method (e.g. AlO, NCP, Bare Metal/Archive, etc.)
replace me
- Are you using CloudfIare, mod_security, or similar? (Yes / No)
- No
Summary of the issue you are facing:
Error message coming aprox. 1~/h.
|Erreur|mail|ServiceException Sync failed for 7:INBOX: Call to undefined method Rubix\ML\Datasets\Unlabeled::numFeatures()
Cron mail sync failed for account 7|
Steps to replicate it (hint: details matter!):
No idea hpw 
Log entries
Nextcloud
{“reqId”:“kBaPz9QmYEyXA6sk9say”,“level”:3,“time”:“2025-04-08T17:05:09+00:00”,“remoteAddr”:“”,“user”:“–”,“app”:“mail”,“method”:“”,“url”:“–”,“message”:“Cron mail sync failed for account 7”,“userAgent”:“–”,“version”:“30.0.8.1”,“exception”:{“Exception”:“OCA\Mail\Exception\ServiceException”,“Message”:“Sync failed for 7:INBOX: Call to undefined method Rubix\ML\Datasets\Unlabeled::numFeatures()”,“Code”:0,“Trace”:[{“file”:“/home/www/www.hephoto.ch/cloud/apps/mail/lib/Service/Sync/ImapToDbSynchronizer.php”,“line”:133,“function”:“sync”,“class”:“OCA\Mail\Service\Sync\ImapToDbSynchronizer”,“type”:“->”,“args”:[“*** sensitive parameters replaced “]},{“file”:”/home/www/www.hephoto.ch/cloud/apps/mail/lib/BackgroundJob/SyncJob.php",“line”:93,“function”:“syncAccount”,“class”:“OCA\Mail\Service\Sync\ImapToDbSynchronizer”,“type”:“->”,“args”:[" sensitive parameters replaced “]},{“file”:”/home/www/www.hephoto.ch/cloud/lib/public/BackgroundJob/Job.php",“line”:61,“function”:“run”,“class”:“OCA\Mail\BackgroundJob\SyncJob”,“type”:“->”},{“file”:“/home/www/www.hephoto.ch/cloud/lib/public/BackgroundJob/TimedJob.php”,“line”:88,“function”:“start”,“class”:“OCP\BackgroundJob\Job”,“type”:“->”},{“file”:“/home/www/www.hephoto.ch/cloud/lib/public/BackgroundJob/TimedJob.php”,“line”:75,“function”:“start”,“class”:“OCP\BackgroundJob\TimedJob”,“type”:“->”},{“file”:“/home/www/www.hephoto.ch/cloud/cron.php”,“line”:162,“function”:“execute”,“class”:“OCP\BackgroundJob\TimedJob”,“type”:“->”}],“File”:“/home/www/www.hephoto.ch/cloud/apps/mail/lib/Service/Sync/ImapToDbSynchronizer.php”,“Line”:282,“Previous”:{“Exception”:“Error”,“Message”:“Call to undefined method Rubix\ML\Datasets\Unlabeled::numFeatures()”,“Code”:0,“Trace”:[{“file”:“/home/www/www.hephoto.ch/cloud/apps/mail/lib/Service/Classification/FeatureExtraction/CompositeExtractor.php”,“line”:53,“function”:“extract”,“class”:“OCA\Mail\Service\Classification\FeatureExtraction\SubjectExtractor”,“type”:“->”},{“function”:“OCA\Mail\Service\Classification\FeatureExtraction\{closure}”,“class”:“OCA\Mail\Service\Classification\FeatureExtraction\CompositeExtractor”,“type”:“::”,“args”:[" sensitive parameters replaced “]},{“file”:”/home/www/www.hephoto.ch/cloud/apps/mail/lib/functions.php",“line”:19,“function”:“array_map”},{“file”:“/home/www/www.hephoto.ch/cloud/apps/mail/lib/Service/Classification/FeatureExtraction/CompositeExtractor.php”,“line”:52,“function”:“OCA\Mail\array_flat_map”},{“file”:“/home/www/www.hephoto.ch/cloud/apps/mail/lib/Service/Classification/ImportanceClassifier.php”,“line”:408,“function”:“extract”,“class”:“OCA\Mail\Service\Classification\FeatureExtraction\CompositeExtractor”,“type”:“->”},{“function”:“OCA\Mail\Service\Classification\{closure}”,“class”:“OCA\Mail\Service\Classification\ImportanceClassifier”,“type”:“::”,“args”:[" sensitive parameters replaced “]},{“file”:”/home/www/www.hephoto.ch/cloud/apps/mail/lib/Service/Classification/ImportanceClassifier.php",“line”:402,“function”:“array_map”},{“file”:“/home/www/www.hephoto.ch/cloud/apps/mail/lib/Service/Classification/ImportanceClassifier.php”,“line”:193,“function”:“getFeaturesAndImportance”,“class”:“OCA\Mail\Service\Classification\ImportanceClassifier”,“type”:“->”},{“file”:“/home/www/www.hephoto.ch/cloud/apps/mail/lib/Service/Classification/ImportanceClassifier.php”,“line”:234,“function”:“buildDataSet”,“class”:“OCA\Mail\Service\Classification\ImportanceClassifier”,“type”:“->”},{“file”:“/home/www/www.hephoto.ch/cloud/apps/mail/lib/Service/Classification/ImportanceClassifier.php”,“line”:442,“function”:“train”,“class”:“OCA\Mail\Service\Classification\ImportanceClassifier”,“type”:“->”},{“file”:“/home/www/www.hephoto.ch/cloud/apps/mail/lib/Service/Classification/NewMessagesClassifier.php”,“line”:85,“function”:“classifyImportance”,“class”:“OCA\Mail\Service\Classification\ImportanceClassifier”,“type”:“->”},{“file”:“/home/www/www.hephoto.ch/cloud/apps/mail/lib/Service/Sync/ImapToDbSynchronizer.php”,“line”:445,“function”:“classifyNewMessages”,“class”:“OCA\Mail\Service\Classification\NewMessagesClassifier”,“type”:“->”},{“file”:“/home/www/www.hephoto.ch/cloud/apps/mail/lib/Service/Sync/ImapToDbSynchronizer.php”,“line”:263,“function”:“runPartialSync”,“class”:“OCA\Mail\Service\Sync\ImapToDbSynchronizer”,“type”:“->”},{“file”:“/home/www/www.hephoto.ch/cloud/apps/mail/lib/Service/Sync/ImapToDbSynchronizer.php”,“line”:133,“function”:“sync”,“class”:“OCA\Mail\Service\Sync\ImapToDbSynchronizer”,“type”:“->”,“args”:[" sensitive parameters replaced “]},{“file”:”/home/www/www.hephoto.ch/cloud/apps/mail/lib/BackgroundJob/SyncJob.php",“line”:93,“function”:“syncAccount”,“class”:“OCA\Mail\Service\Sync\ImapToDbSynchronizer”,“type”:“->”,“args”:[" sensitive parameters replaced ***”]},{“file”:“/home/www/www.hephoto.ch/cloud/lib/public/BackgroundJob/Job.php”,“line”:61,“function”:“run”,“class”:“OCA\Mail\BackgroundJob\SyncJob”,“type”:“->”},{“file”:“/home/www/www.hephoto.ch/cloud/lib/public/BackgroundJob/TimedJob.php”,“line”:88,“function”:“start”,“class”:“OCP\BackgroundJob\Job”,“type”:“->”},{“file”:“/home/www/www.hephoto.ch/cloud/lib/public/BackgroundJob/TimedJob.php”,“line”:75,“function”:“start”,“class”:“OCP\BackgroundJob\TimedJob”,“type”:“->”},{“file”:“/home/www/www.hephoto.ch/cloud/cron.php”,“line”:162,“function”:“execute”,“class”:“OCP\BackgroundJob\TimedJob”,“type”:“->”}],“File”:“/home/www/www.hephoto.ch/cloud/apps/mail/lib/Service/Classification/FeatureExtraction/SubjectExtractor.php”,“Line”:89},“message”:“Cron mail sync failed for account {accountId}”,“exception”:{},“CustomMessage”:“Cron mail sync failed for account 7”}}
### Configuration
#### Nextcloud
The output of `occ config:list system` or similar is best, but, if not possible, the contents of your `config.php` file from `/path/to/nextcloud` is fine (make sure to remove any identifiable information!):
{
“system”: {
“instanceid”: “REMOVED SENSITIVE VALUE”,
“passwordsalt”: “REMOVED SENSITIVE VALUE”,
“secret”: “REMOVED SENSITIVE VALUE”,
“trusted_domains”: [
“www.hephoto.ch”,
“localhost”,
“mail.hephoto.ch”,
“hephoto.ch”,
“hephoto.ch/cloud”
],
“datadirectory”: “REMOVED SENSITIVE VALUE”,
“dbtype”: “mysql”,
“version”: “30.0.8.1”,
“overwrite.cli.url”: “https://www.hephoto.ch/cloud”,
“htaccess.RewriteBase”: “/cloud”,
“dbname”: “REMOVED SENSITIVE VALUE”,
“dbhost”: “REMOVED SENSITIVE VALUE”,
“dbport”: “”,
“dbtableprefix”: “oc_”,
“mysql.utf8mb4”: true,
“dbuser”: “REMOVED SENSITIVE VALUE”,
“dbpassword”: “REMOVED SENSITIVE VALUE”,
“installed”: true,
“mail_from_address”: “REMOVED SENSITIVE VALUE”,
“mail_smtpmode”: “smtp”,
“mail_sendmailmode”: “smtp”,
“mail_domain”: “REMOVED SENSITIVE VALUE”,
“ldapIgnoreNamingRules”: false,
“ldapProviderFactory”: “OCA\User_LDAP\LDAPProviderFactory”,
“default_language”: “fr_CH”,
“default_locale”: “fr_CH”,
“maintenance”: false,
“theme”: “”,
“log_type”: “file”,
“syslog_tag”: “Nextcloud”,
“logfile”: “/var/log/nextcould.log”,
“loglevel”: 3,
“remember_login_cookie_lifetime”: 7200,
“session_lifetime”: 3600,
“session_keepalive”: true,
“trashbin_retention_obligation”: “auto,2”,
“versions_retention_obligation”: “auto,7”,
“tempdirectory”: “/tmp”,
“login_form_autocomplete”: false,
“app_install_overwrite”: [
“calendar”,
“documentserver_community”,
“listman”
],
“default_phone_region”: “CH”,
“memcache.local”: “\OC\Memcache\APCu”,
“allow_local_remote_servers”: true,
“maintenance_window_start”: 1
}
}