[Bug]: Preview Generation Fail - Local Storage

### ⚠️ This issue respects the following points: ⚠️

- [x] This is a **bug**, not a question or a configuration/webserver/proxy issue.
- [x] This issue is **not** already reported on [Github](https://github.com/nextcloud/server/issues?q=is%3Aopen+is%3Aissue+label%3Abug) OR [Nextcloud Community Forum](https://help.nextcloud.com/) _(I've searched it)_.
- [x] Nextcloud Server **is** up to date. See [Maintenance and Release Schedule](https://github.com/nextcloud/server/wiki/Maintenance-and-Release-Schedule) for supported versions.
- [x] I agree to follow Nextcloud's [Code of Conduct](https://nextcloud.com/contribute/code-of-conduct/).

### Bug description

Preview generation fail (because preview folder i'nt created) in NC 32.0.1 (latest).

**Setup:**
- Nextcloud 32 trough docker compose (image: "nextcloud:32.0")
- mariadb
- apps installed (preview generator + memories) : latest
- local volumes mounted trough volumes (docker):
-  - /mnt/DiskCloud/:/var/www/html/data 
-  - /mnt/Photos:/mnt/Photos  (mounted as local storage into nextcloud)

**Issue**: 
- Lot of preview are not generated into the stock photo (and memories) app's.
- I tried with the local generator backend (imagick) and external (imaginary) with same result

**Troubleshoot:**
- I did a lot of troubleshoot, together with previewmanager app
- lib/private/PreviewManager.php call the lib/private/Preview/Generator.php backend.
- lib/private/Preview/Generator.php try to write the preview (which is correctly generated trough the preview generator) in to the /app_xxx/preview/a/b/c/d/e/f/g/photo_id/ folder , which use the lib/private/Files/Node/File.php (trough lib/private/Files/View.php)

**The fwrite fail because the folder /app_xxx/preview/a/b/c/d/e/f/g/photo_id/ is not created.**
This is NOT a file permission issue since the process run as www-data and the permissions are 755 for folders and 644 for files for all the /app_xxx/ folder . (and of course ownership is also www-data).

I tried to manually create all the folder based on the fileid contained in oc_filecache ( matching jpg/JPG ) and after this, all previews are correctly generated.

**==>> It seems to have an issue with the preview directory creation ....** 
Forcing the directory creation in View.php works but it's crappy.


Best regards.




### Steps to reproduce

1.Recreate my setup here above
2.Put 300Gb of jpg in it
3.run php occ preview:generate-all
4.look at the photo (or memories) gallery (lot of preview cannot be created)


### Expected behavior

All preview are correctly generated into the /app_xxxx/a/b/c/d/e/f/g/file_id/ folders.

### Nextcloud Server version

32

### Operating system

Debian/Ubuntu

### PHP engine version

PHP 8.3

### Web server

Apache (supported)

### Database engine version

MariaDB

### Is this bug present after an update or on a fresh install?

Updated from a MINOR version (ex. 32.0.1 to 32.0.2)

### Are you using the Nextcloud Server Encryption module?

Encryption is Disabled

### What user-backends are you using?

- [x] Default user-backend _(database)_
- [ ] LDAP/ Active Directory
- [ ] SSO - SAML
- [ ] Other

### Configuration report

```json
{
    "system": {
        "htaccess.RewriteBase": "\/",
        "memcache.local": "\\OC\\Memcache\\APCu",
        "apps_paths": [
            {
                "path": "\/var\/www\/html\/apps",
                "url": "\/apps",
                "writable": false
            },
            {
                "path": "\/var\/www\/html\/custom_apps",
                "url": "\/custom_apps",
                "writable": true
            }
        ],
        "memcache.distributed": "\\OC\\Memcache\\Redis",
        "memcache.locking": "\\OC\\Memcache\\Redis",
        "redis": {
            "host": "***REMOVED SENSITIVE VALUE***",
            "password": "***REMOVED SENSITIVE VALUE***",
            "port": 6379
        },
        "upgrade.disable-web": true,
        "instanceid": "***REMOVED SENSITIVE VALUE***",
        "passwordsalt": "***REMOVED SENSITIVE VALUE***",
        "secret": "***REMOVED SENSITIVE VALUE***",
        "trusted_domains": [
            "192.168.XXX.YYY",
            "my.domain.com",
            "192.168.XXX.YYY"
        ],
        "trusted_proxies": "***REMOVED SENSITIVE VALUE***",
        "forwarded_for_headers": [
            "HTTP_X_FORWARDED_FOR"
        ],
        "wopi": {
            "allow_hosts": [
                "my.domain.com"
                "collabora.my.domain.com"
            ]
        },
        "datadirectory": "***REMOVED SENSITIVE VALUE***",
        "dbtype": "mysql",
        "version": "32.0.1.2",
        "overwrite.cli.url": "https:\/\/cloud.my.domain.com",
        "overwriteprotocol": "https",
        "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_domain": "***REMOVED SENSITIVE VALUE***",
        "mail_from_address": "***REMOVED SENSITIVE VALUE***",
        "mail_smtpmode": "smtp",
        "mail_smtphost": "***REMOVED SENSITIVE VALUE***",
        "mail_sendmailmode": "smtp",
        "mail_smtpport": "587",
        "mail_smtpauth": true,
        "mail_smtpname": "***REMOVED SENSITIVE VALUE***",
        "mail_smtppassword": "***REMOVED SENSITIVE VALUE***",
        "loglevel": 2,
        "maintenance": false,
        "maintenance_window_start": 1,
        "default_phone_region": "FR",
        "app_install_overwrite": [],
        "memories.max_preview_size": 2048,
        "files_external_allow_create_new_local": true,
        "enabledPreviewProviders": [
            "OC\\Preview\\PNG",
            "OC\\Preview\\JPEG",
            "OC\\Preview\\GIF",
            "OC\\Preview\\BMP",
            "OC\\Preview\\XBitmap",
            "OC\\Preview\\MP3",
            "OC\\Preview\\TXT",
            "OC\\Preview\\MarkDown",
            "OC\\Preview\\PDF",
            "OC\\Preview\\Movie",
            "OC\\Preview\\Image",
            "OC\\Preview\\Imaginary"
        ],
        "memories.vod.ffmpeg": "\/usr\/bin\/ffmpeg",
        "memories.vod.ffprobe": "\/usr\/bin\/ffprobe",
        "preview_max_filesize_image": 50,
        "preview_path": "data\/appdata_xxx\/preview",
        "enable_previews": true,
        "preview_max_x": 2048,
        "preview_max_y": 2048,
        "preview_max_scale_factor": 1,
        "jpeg_quality": 60,
        "preview_max_memory": 512,
        "preview_limit_enforcement": true,
        "memories.gis_type": 1,
        "memories.db.triggers.fcu": true,
        "memories.exiftool": "\/var\/www\/html\/custom_apps\/memories\/bin-ext\/exiftool-amd64-glibc",
        "memories.vod.path": "\/var\/www\/html\/custom_apps\/memories\/bin-ext\/go-vod-amd64",
        "preview_imaginary_url": "***REMOVED SENSITIVE VALUE***",
        "preview_imaginary_key": "***REMOVED SENSITIVE VALUE***",
        "preview_imaginary_allow_insecure": true,
        "memories.imaginary_url": "http:\/\/192.168.XXX.YYY:9000",
        "memories.preview_max_size": 2048,
        "memories.imaginary_proxy": false,
        "memories.vod.disable": false,
        "memories.vod.vaapi": true
    }
}
```

### List of activated Apps

```shell
$ php occ app:list
Enabled:
  - activity: 5.0.0-dev.0
  - bruteforcesettings: 5.0.0-dev.0
  - cloud_federation_api: 1.16.0
  - comments: 1.22.0
  - dashboard: 7.12.0
  - dav: 1.34.2
  - drawio: 3.1.2
  - federatedfilesharing: 1.22.0
  - federation: 1.22.0
  - files: 2.4.0
  - files_external: 1.24.0
  - files_pdfviewer: 5.0.0-dev.0
  - files_reminders: 1.5.0
  - files_sharing: 1.24.0
  - files_trashbin: 1.22.0
  - files_versions: 1.25.0
  - logreader: 5.0.0-dev.0
  - lookup_server_connector: 1.20.0
  - memories: 7.7.0
  - music: 2.4.1
  - nextcloud_announcements: 4.0.0-dev.0
  - notifications: 5.0.0-dev.0
  - oauth2: 1.20.0
  - password_policy: 4.0.0-dev.0
  - photos: 5.0.0-dev.1
  - previewgenerator: 5.10.0
  - privacy: 4.0.0-dev.0
  - profile: 1.1.0
  - provisioning_api: 1.22.0
  - recognize: 10.0.6
  - related_resources: 3.0.0-dev.0
  - richdocuments: 9.0.1
  - serverinfo: 4.0.0-dev.0
  - settings: 1.15.1
  - sharebymail: 1.22.0
  - support: 4.0.0-dev.0
  - survey_client: 4.0.0-dev.0
  - systemtags: 1.22.0
  - tasks: 0.17.1
  - text: 6.0.1
  - theming: 2.7.0
  - twofactor_backupcodes: 1.21.0
  - updatenotification: 1.22.0
  - user_status: 1.12.0
  - viewer: 5.0.0-dev.0
  - webhook_listeners: 1.3.0
  - workflowengine: 2.14.0
Disabled:
  - admin_audit: 1.22.0
  - app_api: 32.0.0 (installed 32.0.0)
  - circles: 32.0.0 (installed 32.0.0)
  - contactsinteraction: 1.13.1 (installed 1.13.1)
  - encryption: 2.20.0
  - files_downloadlimit: 5.0.0-dev.0 (installed 5.0.0-dev.0)
  - firstrunwizard: 5.0.0-dev.0 (installed 5.0.0-dev.0)
  - recommendations: 5.0.0-dev.0 (installed 5.0.0-dev.0)
  - suspicious_login: 10.0.0-dev.0
  - twofactor_nextcloud_notification: 6.0.0-dev.0
  - twofactor_totp: 14.0.0
  - user_ldap: 1.23.0
  - weather_status: 1.12.0 (installed 1.12.0)
```

### Nextcloud Signing status

```shell

```

### Nextcloud Logs

```json
y at /var/www/html/lib/private/Files/Storage/Local.php#302","userAgent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:144.0) Gecko/20100101 Firefox/144.0","version":"32.0.1.2","data":{"app":"PHP"}}
{"reqId":"gVZ9kVqxxeCbruEOtzxb","level":2,"time":"2025-11-18T09:21:04+00:00","remoteAddr":"192.168.XXX.YYY","user":"myusername","app":"PHP","method":"GET","url":"/apps/memories/api/image/preview/235256?c=4efad271b7941b315aabbccf00008bb2&x=256&y=256&a=0","message":"Failed to open stream: No such file or directory at /var/www/html/lib/private/Files/Storage/Local.php#302","userAgent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:144.0) Gecko/20100101 Firefox/144.0","version":"32.0.1.2","data":{"app":"PHP"}}

(cannot open stream since the preview is not generated)
```

### Additional info

see troubleshooting here above.


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[Bug]: Preview Generation Fail - Local Storage #56510

⚠️ This issue respects the following points: ⚠️

Bug description

Steps to reproduce

Expected behavior

Nextcloud Server version

Operating system

PHP engine version

Web server

Database engine version

Is this bug present after an update or on a fresh install?

Are you using the Nextcloud Server Encryption module?

What user-backends are you using?

Configuration report

List of activated Apps

Nextcloud Signing status

Nextcloud Logs

Additional info

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

Uh oh!

[Bug]: Preview Generation Fail - Local Storage #56510

Description

⚠️ This issue respects the following points: ⚠️

Bug description

Steps to reproduce

Expected behavior

Nextcloud Server version

Operating system

PHP engine version

Web server

Database engine version

Is this bug present after an update or on a fresh install?

Are you using the Nextcloud Server Encryption module?

What user-backends are you using?

Configuration report

List of activated Apps

Nextcloud Signing status

Nextcloud Logs

Additional info

Metadata

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

Issue actions