Thumbnail not working, but it seems they did on initial run

ℹ️ Support
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1

Hi everyone! thanks in advance for any support you can provide! Having issues with displaying thumbnails in Photos/Memories and can’t for the life of me figure it out. I’ve tried several things but nothing seems to work. Everything worked fine at some point but any new photos don’t get a thumbnail and some of the previously working thumbnails are gone, especially on videos.

The Basics

  • Nextcloud Server version (e.g., 29.x.x):
    • Nextcloud version: 31.0.7 - 31.0.7.1
  • Operating system and version (e.g., Ubuntu 24.04):
    • Linux 6.8.0-65-generic #68\~22.04.1-Ubuntu SMP PREEMPT_DYNAMIC Tue Jul 15 18:06:34 UTC 2 x86_64
  • Web server and version (e.g, Apache 2.4.25):
    • Apache/2.4.52 (Ubuntu) (fpm-fcgi)
  • Reverse proxy and version _(e.g. nginx 1.27.2)
    • n/a
  • PHP version (e.g, 8.3):
    • 8.4.10
  • Is this the first time you’ve seen this error? (Yes / No):
    • yes, but is a fresh install
  • When did this problem seem to first start?
    • 1 week
  • Installation method (e.g. AlO, NCP, Bare Metal/Archive, etc.)
    • command line?
  • Are you using CloudfIare, mod_security, or similar? (Yes / No)
    • i don't believe so

Summary of the issue you are facing:

I can’t seem to get photo thumbnails to work now with either Photos or Memories apps. Initial run did load up the thumbnails but then new photos that were uploaded for testing purposes do not get a thumbnail. Also, suddenly some of the previously loaded thumbnails are no longer showing, especially on video files (mp4).

Steps to replicate it (hint: details matter!):

  1. log in to Nextcloud
  2. go to photos or memories
  3. see no thumbnails on some photos/videos

Log entries

Nextcloud

Please provide the log entries from your Nextcloud log that are generated during the time of problem (via the Copy raw option from Administration settings->Logging screen or from your nextcloud.log located in your data directory). Feel free to use a pastebin/gist service if necessary.

{"reqId":"VD4mOOX3vw2eupADOMaA","level":3,"time":"2025-08-05T13:32:09+00:00","remoteAddr":"192.168.2.121","user":"OverrRyde","app":"no app in context","method":"GET","url":"/index.php/apps/memories/api/image/preview/26987?c=60fe24e4bd442dd6f469e3ca400dc375&x=454&y=454&a=1","message":"No provider successfully handled the preview generation","userAgent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:141.0) Gecko/20100101 Firefox/141.0","version":"31.0.7.1","data":{"trace":"[{\"file\":\"/var/www/nextcloud/lib/private/Preview/Generator.php\",\"line\":313,\"function\":\"generateProviderPreview\",\"class\":\"OC\\Preview\\Generator\",\"type\":\"->\"},{\"file\":\"/var/www/nextcloud/lib/private/Preview/Generator.php\",\"line\":117,\"function\":\"getMaxPreview\",\"class\":\"OC\\Preview\\Generator\",\"type\":\"->\"},{\"file\":\"/var/www/nextcloud/lib/private/Preview/Generator.php\",\"line\":87,\"function\":\"generatePreviews\",\"class\":\"OC\\Preview\\Generator\",\"type\":\"->\"},{\"file\":\"/var/www/nextcloud/lib/private/PreviewManager.php\",\"line\":161,\"function\":\"getPreview\",\"class\":\"OC\\Preview\\Generator\",\"type\":\"->\"},{\"file\":\"/var/www/nextcloud/apps/memories/lib/Controller/ImageController.php\",\"line\":62,\"function\":\"getPreview\",\"class\":\"OC\\PreviewManager\",\"type\":\"->\"},{\"file\":\"/var/www/nextcloud/apps/memories/lib/UtilController.php\",\"line\":20,\"function\":\"{closure:OCA\\Memories\\Controller\\ImageController::preview():55}\",\"class\":\"OCA\\Memories\\Controller\\ImageController\",\"type\":\"->\"},{\"file\":\"/var/www/nextcloud/apps/memories/lib/Controller/ImageController.php\",\"line\":55,\"function\":\"guardEx\",\"class\":\"OCA\\Memories\\Util\",\"type\":\"::\"},{\"file\":\"/var/www/nextcloud/lib/private/AppFramework/Http/Dispatcher.php\",\"line\":200,\"function\":\"preview\",\"class\":\"OCA\\Memories\\Controller\\ImageController\",\"type\":\"->\"},{\"file\":\"/var/www/nextcloud/lib/private/AppFramework/Http/Dispatcher.php\",\"line\":114,\"function\":\"executeController\",\"class\":\"OC\\AppFramework\\Http\\Dispatcher\",\"type\":\"->\"},{\"file\":\"/var/www/nextcloud/lib/private/AppFramework/App.php\",\"line\":161,\"function\":\"dispatch\",\"class\":\"OC\\AppFramework\\Http\\Dispatcher\",\"type\":\"->\"},{\"file\":\"/var/www/nextcloud/lib/private/Route/Router.php\",\"line\":315,\"function\":\"main\",\"class\":\"OC\\AppFramework\\App\",\"type\":\"::\"},{\"file\":\"/var/www/nextcloud/lib/base.php\",\"line\":1040,\"function\":\"match\",\"class\":\"OC\\Route\\Router\",\"type\":\"->\"},{\"file\":\"/var/www/nextcloud/index.php\",\"line\":24,\"function\":\"handleRequest\",\"class\":\"OC\",\"type\":\"::\"}]"},"id":"68920c324b56a"}

Web Browser

If the problem is related to the Web interface, open your browser inspector Console and Network tabs while refreshing (reloading) and reproducing the problem. Provide any relevant output/errors here that appear.

PASTE

Web server / Reverse Proxy

The output of your Apache/nginx/system log in /var/log/____:

PASTE HERE

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!):

{
    "instanceid": "***REMOVED SENSITIVE VALUE***",
    "passwordsalt": "***REMOVED SENSITIVE VALUE***",
    "secret": "***REMOVED SENSITIVE VALUE***",
    "trusted_domains": [
        "74.XX.XXX.XX",
        "192.168.2.10",
        "nextcloud.REMOVE VALUE.live"
    ],
    "datadirectory": "***REMOVED SENSITIVE VALUE***",
    "dbtype": "mysql",
    "version": "31.0.7.1",
    "overwrite.cli.url": "http:\/\/192.168.2.10",
    "dbname": "***REMOVED SENSITIVE VALUE***",
    "dbhost": "***REMOVED SENSITIVE VALUE***",
    "dbport": "",
    "dbtableprefix": "oc_",
    "mysql.utf8mb4": true,
    "dbuser": "***REMOVED SENSITIVE VALUE***",
    "dbpassword": "***REMOVED SENSITIVE VALUE***",
    "installed": true,
    "app_install_overwrite": [],
    "maintenance": false,
    "default_phone_region": "US",
    "maintenance_window_start": 6,
    "memories.db.triggers.fcu": true,
    "memories.exiftool": "\/var\/www\/nextcloud\/apps\/memories\/bin-ext\/exiftool-amd64-glibc",
    "memories.vod.path": "\/var\/www\/nextcloud\/apps\/memories\/bin-ext\/go-vod-amd64",
    "preview_max_x": 4096,
    "preview_max_y": 4096,
    "enabledPreviewProviders": [
        "OC\\Preview\\Image",
        "OC\\Preview\\Movie",
        "OC\\Preview\\HEIC",
        "OC\\Preview\\TIFF"
    ],
    "memories.gis_type": 1,
    "memories.vod.ffmpeg": "\/usr\/bin\/ffmpeg",
    "memories.vod.ffprobe": "\/usr\/bin\/ffprobe",
    "preview_max_filesize_image": 100,
    "enable_previews": true,
    "memcache.local": "\\OC\\Memcache\\APCu"
}

Apps

The output of occ app:list (if possible).

Enabled:
 - activity: 4.0.0
 - app_api: 5.0.2
 - bruteforcesettings: 4.0.0
 - calendar: 5.3.7
 - circles: 31.0.0
 - comments: 1.21.0
 - contactsinteraction: 1.12.0
 - dashboard: 7.11.0
 - federation: 1.21.0
 - files_downloadlimit: 4.0.0
 - files_external: 1.23.0
 - files_pdfviewer: 4.0.0
 - files_reminders: 1.4.0
 - files_sharing: 1.23.1
 - files_trashbin: 1.21.0
 - files_versions: 1.24.0
 - firstrunwizard: 4.0.0
 - integration_google: 4.1.0
 - logreader: 4.0.0
 - memories: 7.6.1
 - nextcloud_announcements: 3.0.0
 - notes: 4.12.2
 - notifications: 4.0.0
 - password_policy: 3.0.0
 - photos: 4.0.0
 - previewgenerator: 5.9.0
 - privacy: 3.0.0
 - recognize: 9.0.3
 - recommendations: 4.0.0
 - related_resources: 2.0.0
 - richdocuments: 8.7.3
 - richdocumentscode: 25.4.202
 - serverinfo: 3.0.0
 - sharebymail: 1.21.0
 - support: 3.0.0
 - survey_client: 3.0.0
 - systemtags: 1.21.1
 - text: 5.0.0
 - updatenotification: 1.21.0
 - user_status: 1.11.0
 - weather_status: 1.11.0
 - webhook_listeners: 1.2.0
Disabled:
 - admin_audit
 - encryption
 - suspicious_login
 - twofactor_nextcloud_notification
 - twofactor_totp
 - user_ldap
2

FWIW, i did move the data folder to a new hard drive as the one NC was installed on is set to fail and i did not want to risk losing data. So i purchased a new hard drive and move the contents of /var/www/nextcloud/data to /mnt/nas/data

the new folder is owned by www-data

everything else appears to work fine except photos/memories thumbnails and loading

cheers!

EDIT:
im starting to see an issue with SQL data, wondering if this may be the source (or at least part of) the problem.

Currently, sql showing oc_storages as follows:
±-----------±--------------------------------±----------±-------------+
| numeric_id | id | available | last_checked |
±-----------±--------------------------------±----------±-------------+
| 1 | home::Admin | 1 | NULL |
| 2 | local::/mnt/nas/data/ | 1 | NULL |
| 4 | home::OverrRyde | 1 | NULL |
| 5 | local::/var/www/nextcloud/data/ | 1 | NULL |
±-----------±--------------------------------±----------±-------------+

wondering if ID 4 and 5 are the problem since user OverrRyde is my main one i am trying to fix, but as you can see it is point at the old data folder. I tried to update this but getting this error:

MariaDB [nextcloud]> UPDATE oc_storages SET id=‘local::/mnt/nas/data/’ WHERE id=‘local::/var/www/nextcloud/data/’;
ERROR 1062 (23000): Duplicate entry ‘local::/mnt/nas/data/’ for key ‘storages_id_index’

Hope this is where the problem is but can’t seem to be able to update that.

thanks!

3

maybe HowTo: Change / Move data directory after installation helps

4

Thanks @wwe , checked it out, appears that the solution might not work for me.

I was actually able to cleanup the database and the home directory and as i suspected, i don’t believe that was the issue since everything is and has been working fine since original install.

One new thing i noticed was the fact that after cleaning up oc_storages and oc_filecache and redoing a full scan, pre-generate and cleanup using occ, all the pictures are blank from a thumbnail standpoint until i manually zoom in on the picture, at which point it shows up, same for mp4 videos.

HOWEVER! i uploaded a brand spanking new picture that was in PNG format and that loaded with a thumbnail, so it appears the issue is with jpg and mp4 files and it feels like i’ve tried everything under the sun and can’t get anything to work.

At this point, i am considering completely re-installing everything and re-uploading all my pictures (which is the only thing so far i had on the server) but installing on my 2ndary hard drive.

thoughts?

5

The underlying cause though is still adjusting of the datadirectory without simultaneously either changing the db or doing the symbolic link[1].

Previews are stored as part AppData underneath your configured datadirectory . The occ files:scan-app-data might be helpful here. But the real issue is sorting out the overlapping db entries.

[1] Admin Manual - Troubleshooting data directory: Moving

6

Thanks @jtr !

I did the changes needed to the oc_storages DB and it reflects my current data directory. I also ran a cleanup or oc_filecache and rescanned all the photos again to no avail.

Testing with new PNG image does generate thumbnails, uploading a new JPG does nothing. What would cause this considering everything was “cleaned” and confirmed config files has what is needed and apps needed installed as well (memories, preview generator, ffpmeg, etc). NC log keeps insisting on the fact that no preview generator was able to handle the generating.

Really trying to avoid a reinstall and want to keep using my new hard drive but it appears that NC works best when ran on main hard drive, but not sure.

Cheers

7

sounds like you didn’t scan appdata as jtr recommended

then you should increase log level and check errors while upload and first view of new file, share the logs so people can check themself. use search the issues with preview are not really rare - even unrelated looking topics might give you troubleshooting hints.

8

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