Preview generation fails, if richdocuments are active

nofferel · June 25, 2026, 11:54am

The Basics

Nextcloud Server version (e.g., 29.x.x):
- 33.0.5.1
Operating sysietem and version (e.g., Ubuntu 24.04):
- Debian Trixe
Web server and version (e.g, Apache 2.4.25):
- nginx 2.6.3
PHP version (e.g, 8.3):
- 8.4
Is this the first time you’ve seen this error? (Yes / No):
- yes
When did this problem seem to first start?
- no idea
Installation method (e.g. AlO, NCP, Bare Metal/Archive, etc.)
- archive

Summary of the issue you are facing:

When is try to generate previews with either occ preview:pre-generate or occ preview:generate-all, i get the following error and the script exits:

An unhandled exception has been thrown:
TypeError: fclose(): supplied resource is not a valid stream resource in /var/www/nextcloud/apps/richdocuments/lib/Service/RemoteService.php:72
Stack trace:
#0 /var/www/nextcloud/apps/richdocuments/lib/Service/RemoteService.php(72): fclose()
#1 /var/www/nextcloud/apps/richdocuments/lib/Preview/Office.php(55): OCA\\Richdocuments\\Service\\RemoteService->convertFileTo()
#2 /var/www/nextcloud/lib/private/Preview/GeneratorHelper.php(25): OCA\\Richdocuments\\Preview\\Office->getThumbnail()
#3 /var/www/nextcloud/lib/private/Preview/Generator.php(381): OC\\Preview\\GeneratorHelper->getThumbnail()
#4 /var/www/nextcloud/lib/private/Preview/Generator.php(335): OC\\Preview\\Generator->generateProviderPreview()
#5 /var/www/nextcloud/lib/private/Preview/Generator.php(126): OC\\Preview\\Generator->getMaxPreview()
#6 /var/www/nextcloud/lib/private/PreviewManager.php(185): OC\\Preview\\Generator->generatePreviews()
#7 /var/www/nextcloud/apps/previewgenerator/lib/Service/PreGenerateService.php(160): OC\\PreviewManager->generatePreviews()
#8 /var/www/nextcloud/apps/previewgenerator/lib/Service/PreGenerateService.php(141): OCA\\PreviewGenerator\\Service\\PreGenerateService->processFile()
#9 /var/www/nextcloud/apps/previewgenerator/lib/Service/PreGenerateService.php(110): OCA\\PreviewGenerator\\Service\\PreGenerateService->processRow()
#10 /var/www/nextcloud/apps/previewgenerator/lib/Service/PreGenerateService.php(73): OCA\\PreviewGenerator\\Service\\PreGenerateService->startProcessing()
#11 /var/www/nextcloud/apps/previewgenerator/lib/Command/PreGenerate.php(42): OCA\\PreviewGenerator\\Service\\PreGenerateService->preGenerate()
#12 /var/www/nextcloud/3rdparty/symfony/console/Command/Command.php(326): OCA\\PreviewGenerator\\Command\\PreGenerate->execute()
#13 /var/www/nextcloud/3rdparty/symfony/console/Application.php(1083): Symfony\\Component\\Console\\Command\\Command->run()
#14 /var/www/nextcloud/3rdparty/symfony/console/Application.php(324): Symfony\\Component\\Console\\Application->doRunCommand()
#15 /var/www/nextcloud/3rdparty/symfony/console/Application.php(175): Symfony\\Component\\Console\\Application->doRun()
#16 /var/www/nextcloud/lib/private/Console/Application.php(187): Symfony\\Component\\Console\\Application->run()
#17 /var/www/nextcloud/console.php(92): OC\\Console\\Application->run()
#18 /var/www/nextcloud/occ(33): require_once('...')
#19 {main}

Since richdocuments seems to the root cause, i have disabled via occ apps:disable richdocuments. After that, preview generation works fine without errors.

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

See description above

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***",
        "serverid": 1,
        "trusted_domains": [
            "***REMOVED SENSITIVE VALUE***"
        ],
        "datadirectory": "***REMOVED SENSITIVE VALUE***",
        "version": "33.0.5.1",
        "overwrite.cli.url": "***REMOVED SENSITIVE VALUE***",
        "dbtype": "mysql",
        "dbname": "***REMOVED SENSITIVE VALUE***",
        "dbuser": "***REMOVED SENSITIVE VALUE***",
        "dbpassword": "***REMOVED SENSITIVE VALUE***",
        "dbhost": "***REMOVED SENSITIVE VALUE***",
        "dbtableprefix": "oc_",
        "mysql.utf8mb4": true,
        "installed": true,
        "default_language": "de",
        "default_timezone": "Europe\/Amsterdam",
        "memories.db.triggers.fcu": true,
        "memories.exiftool": "\/var\/www\/nextcloud\/apps\/memories\/bin-ext\/exiftool-aarch64-glibc",
        "memories.vod.path": "\/var\/www\/nextcloud\/apps\/memories\/bin-ext\/go-vod-aarch64",
        "memories.vod.ffmpeg": "\/usr\/bin\/ffmpeg",
        "memories.vod.ffprobe": "\/usr\/bin\/ffprobe",
        "memories.vod.disable": true,
        "memories.video_default_quality": "-2",
        "memories.vod.use_transpose": true,
        "memories.vod.use_gop_size": true,
        "memories.gis_type": 1,
        "memories.index.mode": "3",
        "memories.index.path.blacklist": "\\\/@(Recycle|eaDir|calibre)\\\/",
        "memories.index.path": "\/Photos",
        "enable_previews": true,
        "enabledPreviewProviders": [
            "OC\\Preview\\JPEG",
            "OC\\Preview\\HEIC",
            "OC\\Preview\\WEBP",
            "OC\\Preview\\MP3",
            "OC\\Preview\\Image",
            "OC\\Preview\\Movie"
        ],
        "preview_max_x": 1920,
        "preview_max_y": 1920,
        "preview_max_scale_factor": 1,
        "preview_max_filesize_image": 100,
        "jpeg_quality": 60,
        "default_phone_region": "EN",
        "integrity.check.disabled": false,
        "knowledgebaseenabled": false,
        "mail_smtpmode": "smtp",
        "mail_sendmailmode": "pipe",
        "mail_from_address": "***REMOVED SENSITIVE VALUE***",
        "mail_domain": "***REMOVED SENSITIVE VALUE***",
        "mail_smtphost": "***REMOVED SENSITIVE VALUE***",
        "mail_smtpauth": true,
        "mail_smtpport": "465",
        "debug": false,
        "overwriteprotocol": "https",
        "activity_expire_days": 14,
        "auth.bruteforce.protection.enabled": true,
        "ratelimit.protection.enabled": true,
        "trashbin_retention_obligation": "auto, 7",
        "logfile": "\/var\/log\/nextcloud\/nextcloud.log",
        "logtimezone": "Europe\/Amsterdam",
        "loglevel": 2,
        "log_rotate_size": 0,
        "remember_login_cookie_lifetime": 1296000,
        "session_lifetime": 86400,
        "session_keepalive": true,
        "auto_logout": true,
        "profile.enabled": false,
        "memcache.local": "\\OC\\Memcache\\APCu",
        "memcache.locking": "\\OC\\Memcache\\Redis",
        "redis": {
            "host": "***REMOVED SENSITIVE VALUE***",
            "port": 0,
            "timeout": 1,
            "password": "***REMOVED SENSITIVE VALUE***"
        },
        "app_install_overwrite": [],
        "twofactor_enforced": "true",
        "twofactor_enforced_groups": [],
        "twofactor_enforced_excluded_groups": [
            "test"
        ],
        "defaultapp": "files",
        "forbidden_filename_characters": [
            "<",
            ">",
            ":",
            "\"",
            "|",
            "?",
            "*",
            "\\",
            "\/"
        ],
        "forbidden_filename_extensions": [
            " ",
            ".",
            ".filepart",
            ".part"
        ],
        "filesystem_check_changes": 0,
        "maintenance_window_start": 1,
        "maintenance": false,
        "trusted_proxies": "***REMOVED SENSITIVE VALUE***",
        "theme": "",
        "cron_log": true,
        "forbidden_filenames": [
            ".htaccess",
            "Thumbs.db",
            "thumbs.db"
        ],
        "forbidden_filename_basenames": [
            "con",
            "prn",
            "aux",
            "nul",
            "com0",
            "com1",
            "com2",
            "com3",
            "com4",
            "com5",
            "com6",
            "com7",
            "com8",
            "com9",
            "com\u00b9",
            "com\u00b2",
            "com\u00b3",
            "lpt0",
            "lpt1",
            "lpt2",
            "lpt3",
            "lpt4",
            "lpt5",
            "lpt6",
            "lpt7",
            "lpt8",
            "lpt9",
            "lpt\u00b9",
            "lpt\u00b2",
            "lpt\u00b3"
        ],
        "mail_smtpsecure": "ssl",
        "mail_smtpname": "***REMOVED SENSITIVE VALUE***",
        "mail_smtppassword": "***REMOVED SENSITIVE VALUE***"
    }
}

Apps

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

Enabled:
  - bruteforcesettings: 6.0.0
  - calendar: 6.5.0
  - cloud_federation_api: 1.17.0
  - contacts: 8.7.2
  - dav: 1.36.0
  - dav_push: 1.0.1
  - federatedfilesharing: 1.23.0
  - files: 2.5.0
  - files_external: 1.25.1
  - files_pdfviewer: 6.0.0
  - files_sharing: 1.25.2
  - files_trashbin: 1.23.0
  - logreader: 6.0.0
  - lookup_server_connector: 1.21.0
  - memories: 8.0.1
  - music: 3.1.0
  - notifications: 6.0.0
  - notify_push: 1.3.3
  - oauth2: 1.21.0
  - password_policy: 5.0.0
  - photos: 6.0.0
  - previewgenerator: 5.13.0
  - profile: 1.2.0
  - provisioning_api: 1.23.0
  - richdocuments: 10.2.0
  - richdocumentscode_arm64: 26.4.104
  - serverinfo: 5.0.0
  - settings: 1.16.0
  - suspicious_login: 11.0.0
  - systemtags: 1.23.0
  - text: 7.0.1
  - theming: 2.8.0
  - theming_customcss: 1.20.0
  - twofactor_backupcodes: 1.22.0
  - twofactor_totp: 15.0.0
  - updatenotification: 1.23.0
  - user_migration: 10.3.0
  - viewer: 6.0.0
  - workflowengine: 2.15.0
Disabled:
  - activity: 6.0.0 (installed 4.0.0)
  - admin_audit: 1.23.0 (installed 1.21.0)
  - app_api: 33.0.0 (installed 5.0.2)
  - circles: 33.0.0 (installed 32.0.0)
  - comments: 1.23.0 (installed 1.21.0)
  - contactsinteraction: 1.14.1 (installed 1.12.0)
  - dashboard: 7.13.0 (installed 7.11.0)
  - encryption: 2.21.0 (installed 2.19.0)
  - federation: 1.23.0 (installed 1.21.0)
  - files_downloadlimit: 5.1.0 (installed 4.0.0)
  - files_reminders: 1.6.0 (installed 1.4.0)
  - files_versions: 1.26.0 (installed 1.24.0)
  - firstrunwizard: 6.0.0 (installed 4.0.0)
  - mail: 5.10.3 (installed 5.10.3)
  - nextcloud_announcements: 5.0.0 (installed 3.0.0)
  - privacy: 5.0.0 (installed 3.0.0)
  - recommendations: 6.0.0 (installed 4.0.0)
  - related_resources: 4.0.0 (installed 4.0.0-dev.0)
  - sharebymail: 1.23.0 (installed 1.21.0)
  - support: 5.0.0 (installed 3.0.0)
  - survey_client: 5.0.0 (installed 5.0.0-dev.0)
  - testing: 1.23.0
  - twofactor_nextcloud_notification: 7.0.0
  - user_ldap: 1.24.0
  - user_status: 1.13.0 (installed 1.11.0)
  - weather_status: 1.13.0 (installed 1.13.0)
  - webhook_listeners: 1.5.0 (installed 1.5.0)

Any ideas what i could do?

aschrage · June 25, 2026, 2:13pm

Yes, I’m facing the same problem on Nextcloud 32.0.12 and richdocuments version 9.1.0.

Seems to be a known bug:

github.com/nextcloud/richdocuments

Office preview fails on PHP 8: TypeError "fclose(): supplied resource is not a valid stream resource" (double fclose in RemoteService::convertFileTo)

offen 11:55AM - 16 Jun 26 UTC

bygadd

### Describe the bug Generating a preview/thumbnail for any Office document thr…ows a `TypeError` and the preview is never produced. It happens both for on-demand thumbnails and for the `previewgenerator` cron job. On a busy instance this floods `nextcloud.log` (hundreds of errors/day), and a stuck `PreviewGenerator` job retries the same file indefinitely. ### Environment - richdocuments **10.2.0** - Nextcloud **33.0.5** - PHP **8.3.6** - Collabora Online reachable and healthy (`/hosting/discovery` and `/hosting/capabilities` → HTTP 200) ### Steps to reproduce 1. Configure richdocuments with a working Collabora server. 2. Request a preview/thumbnail of any `.docx` / `.xlsx` / `.odt` (open it in Files, or let `previewgenerator` run). 3. Observe the error in `nextcloud.log`. ### Expected behaviour A PNG preview is generated (Collabora converts the file successfully). ### Actual behaviour ``` TypeError: fclose(): supplied resource is not a valid stream resource at apps/richdocuments/lib/Service/RemoteService.php line 72 (fclose) at apps/richdocuments/lib/Preview/Office.php line 55 (convertFileTo) ``` ### Root cause In `RemoteService::convertFileTo()` the stream is opened, handed to `convertTo()`, and then closed in a `finally`: ```php $stream = fopen($fileName, 'rb'); if ($stream === false) { throw new Exception('Failed to open stream'); } try { return $this->convertTo($file->getName(), $stream, $format, [], $timeout); } finally { fclose($stream); // line 72 } ``` `convertTo()` passes that same resource to Guzzle as a multipart body: ```php $options['multipart'] = [[ 'name' => $filename, 'filename' => $filename, 'contents' => $stream ]]; $response = $client->post($collaboraUrl . '/cool/convert-to/' . $format, $options); ``` Guzzle wraps the resource in a PSR-7 stream and **closes the underlying resource once the request body has been sent**. When control returns to `convertFileTo()`, the `finally` calls `fclose()` on an already-closed resource. On PHP 8 this is a fatal `TypeError` (PHP 7 only raised a warning). Because the throw happens inside `finally`, it **replaces the return value**, so preview generation fails *even when Collabora converted the file successfully*. ### Suggested fix Guard the close so it never runs on a consumed/closed resource: ```php } finally { if (is_resource($stream)) { fclose($stream); } } ``` (Alternatively, detach the stream or let Guzzle own its lifecycle.) --- *Diagnosis assisted by an AI coding agent; verified on a live instance.*

nofferel · June 26, 2026, 7:33am

So this seems to be fixed with richdocuments v11.0.0 which is already released in GitHub 2 weeks ago. But when i check with occ app:list, i see that im at richdocuments: 10.2.0 and occ app:update richdocuments gives me richdocuments is up-to-date or no updates could be found

Why is there no newer version?

nofferel · June 26, 2026, 7:46am

Ahh ok, got it. v11.0.0 is only compatible with NC 34, but i got no Update Notification for my instance. Have now manually and git v11.0.0 for richdocuments. I will check later, if this solves the issue

nofferel · June 26, 2026, 8:10am

Update to NC 34 was successful installed now. Richdocuments is on v11.00. But Memories and more important previewgenartor was not available for NC 34. After force activating Memories and Previewgenerator, the error is still there and not fixed.

Adding the suggested fix, fixes it manually.