OCA Mail Exception ServiceException: Could not deserialize persisted classifier

Steps to reproduce

1. Use the mail app with a lot of emails
2. I dont know what sort of emails might cause this problem
3. If I did, maybe I could do something about it

Expected behavior

No errors

Also, in my directory /var/www/vhosts/reeves.one/oc-data/appdata_oc9765749522/mail/classifiers there are 26344 files, from June 2021 on. Can this be cleaned up?

Actual behavior

`[mail] Warnung: OCA\Mail\Exception\ServiceException: Could not deserialize persisted classifier 26315: Unrecognized message format. at <>

0. /var/www/vhosts/example.com/owncloud.example.com/apps/mail/lib/Service/Classification/PersistenceService.php line 165
   OCA\Mail\Service\Classification\PersistenceService->load()
1. /var/www/vhosts/example.com/owncloud.example.com/apps/mail/lib/Service/Classification/ImportanceClassifier.php line 306
   OCA\Mail\Service\Classification\PersistenceService->loadLatest()
2. /var/www/vhosts/example.com/owncloud.example.com/apps/mail/lib/Listener/NewMessageClassificationListener.php line 121
   OCA\Mail\Service\Classification\ImportanceClassifier->classifyImportance()
3. /var/www/vhosts/example.com/owncloud.example.com/lib/private/EventDispatcher/ServiceEventListener.php line 86
   OCA\Mail\Listener\NewMessageClassificationListener->handle()
4. /var/www/vhosts/example.com/owncloud.example.com/3rdparty/symfony/event-dispatcher/EventDispatcher.php line 251
   OC\EventDispatcher\ServiceEventListener->__invoke()
5. /var/www/vhosts/example.com/owncloud.example.com/3rdparty/symfony/event-dispatcher/EventDispatcher.php line 73
   Symfony\Component\EventDispatcher\EventDispatcher->callListeners()
6. /var/www/vhosts/example.com/owncloud.example.com/lib/private/EventDispatcher/EventDispatcher.php line 87
   Symfony\Component\EventDispatcher\EventDispatcher->dispatch()
7. /var/www/vhosts/example.com/owncloud.example.com/apps/mail/lib/Service/Sync/ImapToDbSynchronizer.php line 404
   OC\EventDispatcher\EventDispatcher->dispatch()
8. /var/www/vhosts/example.com/owncloud.example.com/apps/mail/lib/Service/Sync/ImapToDbSynchronizer.php line 236
   OCA\Mail\Service\Sync\ImapToDbSynchronizer->runPartialSync()
9. /var/www/vhosts/example.com/owncloud.example.com/apps/mail/lib/Service/Sync/ImapToDbSynchronizer.php line 137
   OCA\Mail\Service\Sync\ImapToDbSynchronizer->sync("*** sensitive parameters replaced ***")
10. /var/www/vhosts/example.com/owncloud.example.com/apps/mail/lib/BackgroundJob/SyncJob.php line 110
    OCA\Mail\Service\Sync\ImapToDbSynchronizer->syncAccount("*** sensitive parameters replaced ***")
11. /var/www/vhosts/example.com/owncloud.example.com/lib/public/BackgroundJob/Job.php line 78
    OCA\Mail\BackgroundJob\SyncJob->run()
12. /var/www/vhosts/example.com/owncloud.example.com/lib/public/BackgroundJob/TimedJob.php line 103
    OCP\BackgroundJob\Job->start()
13. /var/www/vhosts/example.com/owncloud.example.com/lib/public/BackgroundJob/TimedJob.php line 93
    OCP\BackgroundJob\TimedJob->start()
14. /var/www/vhosts/example.com/owncloud.example.com/cron.php line 152
    OCP\BackgroundJob\TimedJob->execute()

Caused by:

Rubix\ML\Exceptions\RuntimeException: Unrecognized message format. at <>

0. /var/www/vhosts/example.com/owncloud.example.com/apps/mail/vendor/rubix/ml/src/PersistentModel.php line 59
   Rubix\ML\Serializers\RBX->deserialize()
1. /var/www/vhosts/example.com/owncloud.example.com/apps/mail/lib/Service/Classification/PersistenceService.php line 205
   Rubix\ML\PersistentModel::load()
2. /var/www/vhosts/example.com/owncloud.example.com/apps/mail/lib/Service/Classification/PersistenceService.php line 165
   OCA\Mail\Service\Classification\PersistenceService->load()
3. /var/www/vhosts/example.com/owncloud.example.com/apps/mail/lib/Service/Classification/ImportanceClassifier.php line 306
   OCA\Mail\Service\Classification\PersistenceService->loadLatest()
4. /var/www/vhosts/example.com/owncloud.example.com/apps/mail/lib/Listener/NewMessageClassificationListener.php line 121
   OCA\Mail\Service\Classification\ImportanceClassifier->classifyImportance()
5. /var/www/vhosts/example.com/owncloud.example.com/lib/private/EventDispatcher/ServiceEventListener.php line 86
   OCA\Mail\Listener\NewMessageClassificationListener->handle()
6. /var/www/vhosts/example.com/owncloud.example.com/3rdparty/symfony/event-dispatcher/EventDispatcher.php line 251
   OC\EventDispatcher\ServiceEventListener->__invoke()
7. /var/www/vhosts/example.com/owncloud.example.com/3rdparty/symfony/event-dispatcher/EventDispatcher.php line 73
   Symfony\Component\EventDispatcher\EventDispatcher->callListeners()
8. /var/www/vhosts/example.com/owncloud.example.com/lib/private/EventDispatcher/EventDispatcher.php line 87
   Symfony\Component\EventDispatcher\EventDispatcher->dispatch()
9. /var/www/vhosts/example.com/owncloud.example.com/apps/mail/lib/Service/Sync/ImapToDbSynchronizer.php line 404
   OC\EventDispatcher\EventDispatcher->dispatch()
10. /var/www/vhosts/example.com/owncloud.example.com/apps/mail/lib/Service/Sync/ImapToDbSynchronizer.php line 236
    OCA\Mail\Service\Sync\ImapToDbSynchronizer->runPartialSync()
11. /var/www/vhosts/example.com/owncloud.example.com/apps/mail/lib/Service/Sync/ImapToDbSynchronizer.php line 137
    OCA\Mail\Service\Sync\ImapToDbSynchronizer->sync("*** sensitive parameters replaced ***")
12. /var/www/vhosts/example.com/owncloud.example.com/apps/mail/lib/BackgroundJob/SyncJob.php line 110
    OCA\Mail\Service\Sync\ImapToDbSynchronizer->syncAccount("*** sensitive parameters replaced ***")
13. /var/www/vhosts/example.com/owncloud.example.com/lib/public/BackgroundJob/Job.php line 78
    OCA\Mail\BackgroundJob\SyncJob->run()
14. /var/www/vhosts/example.com/owncloud.example.com/lib/public/BackgroundJob/TimedJob.php line 103
    OCP\BackgroundJob\Job->start()
15. /var/www/vhosts/example.com/owncloud.example.com/lib/public/BackgroundJob/TimedJob.php line 93
    OCP\BackgroundJob\TimedJob->start()
16. /var/www/vhosts/example.com/owncloud.example.com/cron.php line 152
    OCP\BackgroundJob\TimedJob->execute()

at 2023-04-24T15:30:03+00:00`

Mail app version

3.1.1

Mailserver or service

Postfix (run under Plesk)

Operating system

Debian 10

PHP engine version

PHP 8.1

Web server

Nginx

Database

MariaDB

Additional info

There are three classifiers being complained about, but two are identical, here are the two causing messages:

O:31:"Rubix\ML\Classifiers\GaussianNB":5:{s:12:"258714;}s:12:"i:1;d:0.99917495319342;i:2;d:0.13576235355309604;i:3;d:0.021654749744637342;}s:1:"i";a:4:{i:0;d:1;i:1;d:0.76190476190476 19;i:2;d:0.14285714285714285;i:3;d:0;}}s:12:"d:0.05229874859502177;i:3;d:0.0038620217624246358;}s:1:"i";a:4:{i:0;d:1.0E-8;i:1;d:0.11791383219954649;i:2;d:0.098639455 78231291;i:3;d:1.0E-8;}}}

O:31:"Rubix\ML\Classifiers\GaussianNB":5:{s:12:"39435;}s:12:"16391844437156;i:1;d:1;i:2;d:0.12667817559299138;i:3;d:0.03952569169960475;}s:2:"ni";a:4:{i:0;d:0.019733516254062056;i:1 ;d:1;i:2;d:0.09390873324901736;i:3;d:0.017375968100605484;}}s:12:"6;i:1;d:1.0E-8;i:2;d:0.033438734413303875;i:3;d:0.0027683606992766627;}s:2:"ni";a:4:{i:0;d:0.0037046587207046977;i:1;d:1 .0E-8;i:2;d:0.027757771656291085;i:3;d:0.0005322342226798502;}}}

Can I delete all these classifiers, so that NC-Mail will recreate the ones it needs?

Thanks, Tim

Start with apps/mail/lib/Service/Classification/PersistenceService.php, especially load() and loadLatest(), then trace their use from ImportanceClassifier.php. Inspect how the classifier files in the appdata mail/classifiers directory are persisted and loaded; done means establishing why the serialized files cannot be deserialized and defining safe cleanup or recovery behavior without recurring warnings.