# Seit dem Update auf die neuste Version Fehler beim cron von preview

**URL:** <https://help.nextcloud.com/t/seit-dem-update-auf-die-neuste-version-fehler-beim-cron-von-preview/248171>\
**Category:** 🌐 International support\
**Tags:** deutsch-german\
**Created:** [August 16, 2026, 3:58pm UTC](https://help.nextcloud.com/t/seit-dem-update-auf-die-neuste-version-fehler-beim-cron-von-preview/248171 "2026-08-16T15:58:25Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![lugau45](https://help.nextcloud.com/letter_avatar/lugau45/32/5_5575768a8748004e209b776fc1b2916d.png) [@lugau45](https://help.nextcloud.com/u/lugau45)\
**Post date:** [August 16, 2026, 3:58pm UTC](https://help.nextcloud.com/t/seit-dem-update-auf-die-neuste-version-fehler-beim-cron-von-preview/248171/1 "2026-08-16T15:58:25Z")

</div>

Der cron wird wie folgt ausgeführt bisher ohne Probleme.

> Cron [nextcloud@s10w](mailto:nextcloud@s10w) /opt/keyhelp/php/8.5/bin/php -f /home/users/nextcloud/www/occ preview:pre-generate \> /dev/null

Das steht in der Mail

> 2026-08-16T15:50:02+00:00  
> 2026-08-16T15:50:02+00:00 In DbalException.php line 50:  
> 2026-08-16T15:50:02+00:00  
> 2026-08-16T15:50:02+00:00 An exception occurred while executing a query: SQLSTATE[23000]: Integrity c  
> 2026-08-16T15:50:02+00:00 onstraint violation: 1052 Column ‘file\_id’ in WHERE is ambiguous  
> 2026-08-16T15:50:02+00:00  
> 2026-08-16T15:50:02+00:00  
> 2026-08-16T15:50:02+00:00 In ExceptionConverter.php line 74:  
> 2026-08-16T15:50:02+00:00  
> 2026-08-16T15:50:02+00:00 An exception occurred while executing a query: SQLSTATE[23000]: Integrity c  
> 2026-08-16T15:50:02+00:00 onstraint violation: 1052 Column ‘file\_id’ in WHERE is ambiguous  
> 2026-08-16T15:50:02+00:00  
> 2026-08-16T15:50:02+00:00  
> 2026-08-16T15:50:02+00:00 In Exception.php line 24:  
> 2026-08-16T15:50:02+00:00  
> 2026-08-16T15:50:02+00:00 SQLSTATE[23000]: Integrity constraint violation: 1052 Column ‘file\_id’ in W  
> 2026-08-16T15:50:02+00:00 HERE is ambiguous  
> 2026-08-16T15:50:02+00:00  
> 2026-08-16T15:50:02+00:00  
> 2026-08-16T15:50:02+00:00 In Statement.php line 130:  
> 2026-08-16T15:50:02+00:00  
> 2026-08-16T15:50:02+00:00 SQLSTATE[23000]: Integrity constraint violation: 1052 Column ‘file\_id’ in W  
> 2026-08-16T15:50:02+00:00 HERE is ambiguous  
> 2026-08-16T15:50:02+00:00  
> 2026-08-16T15:50:02+00:00  
> 2026-08-16T15:50:02+00:00 preview:pre-generate  
> 2026-08-16T15:50:02+00:00

---

<div class="post-metadata">

**Author:** ![scubamuc](https://help.nextcloud.com/user_avatar/help.nextcloud.com/scubamuc/32/63165_2.png) [@scubamuc](https://help.nextcloud.com/u/scubamuc)\
**Post date:** [August 16, 2026, 5:59pm UTC](https://help.nextcloud.com/t/seit-dem-update-auf-die-neuste-version-fehler-beim-cron-von-preview/248171/2 "2026-08-16T17:59:18Z")

</div>

> <https://github.com/nextcloud/server/issues/63229>
>
> \### ⚠️ This issue respects the following points: ⚠️
> 
> \- \[x\] This is a \*\*bug\*\*, no…t 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 fails on MySQL/MariaDB with:
> \`\`\`
> SQLSTATE\[23000\]: Integrity constraint violation: 1052 Column 'file\_id' in WHERE is ambiguous
> \`\`\`
> 
> The error is thrown from \`OC\\Preview\\Db\\PreviewMapper::getPreviewForSpecification()\` every time a preview is saved (\`Generator::savePreview()\`). In my case it surfaces via the Preview Generator app background job (\`OCA\\PreviewGenerator\\BackgroundJob\\PreviewJob\`), but the affected code is in \*\*server core\*\*, so on-the-fly preview generation is affected as well.
> 
> \### Root cause analysis
> 
> \`PreviewMapper::joinLocation()\` joins three tables:
> 
> \- \`previews\` (alias \`p\`)
> \- \`preview\_locations\` (alias \`l\`)
> \- \`preview\_versions\` (alias \`v\`)
> 
> Both \`previews\` (\`p\`) and \`preview\_versions\` (\`v\`) contain a \`file\_id\` column.
> 
> \`getPreviewForSpecification()\` builds WHERE conditions from parameter keys \*\*without a table alias\*\*:
> \`\`\`php
> public function getPreviewForSpecification(array $parameters): ?Preview {
> $qb = $this-\>db-\>getQueryBuilder();
> $this-\>joinLocation($qb);
> 
> foreach ($parameters as $key =\> $value) {
> $qb-\>andWhere($qb-\>expr()-\>eq($key, $qb-\>createNamedParameter($value)));
> }
> ...
> }
> \`\`\`
> 
> When \`$parameters\` contains \`file\_id\`, MySQL/MariaDB rejects the query with error 1052 because the column reference is ambiguous.
> 
> The same problem exists in \`getByFileId()\`:
> \`\`\`php
> public function getByFileId(int $fileId): \\Generator {
> $selectQb = $this-\>db-\>getQueryBuilder();
> $this-\>joinLocation($selectQb)
> -\>where($selectQb-\>expr()-\>eq('file\_id', $selectQb-\>createNamedParameter($fileId, IQueryBuilder::PARAM\_INT)));
> ...
> }
> \`\`\`
> 
> Note that the neighboring method \`getAvailablePreviewsForFile()\` does it correctly (\`'p.file\_id'\`), so this looks like an oversight.
> 
> \### Suggested fix
> 
> Prefix the columns with the proper table alias, e.g.:
> \`\`\`php
> foreach ($parameters as $key =\> $value) {
> $alias = ($key === 'version') ? 'v.' : 'p.';
> $qb-\>andWhere($qb-\>expr()-\>eq($alias . $key, $qb-\>createNamedParameter($value)));
> }
> \`\`\`
> 
> and in \`getByFileId()\`:
> \`\`\`php
> \-\>where($selectQb-\>expr()-\>eq('p.file\_id', $selectQb-\>createNamedParameter($fileId, IQueryBuilder::PARAM\_INT)));
> \`\`\`
> 
> I have applied this patch locally and can confirm the error disappears and previews are generated correctly.
> 
> \### Steps to reproduce
> 
> 1. Run Nextcloud 34.0.3/34.0.4 on MySQL or MariaDB.
> 2. Upload any image file (or install the Preview Generator app and wait for the background job / run \`occ preview:generate-all\`).
> 3. Preview generation triggers \`Generator::savePreview()\` → \`PreviewMapper::getPreviewForSpecification()\` and fails with SQL error 1052; check \`nextcloud.log\`.
> 
> 
> 
> \### Expected behavior
> 
> Previews are generated and stored without SQL errors.
> 
> \### Nextcloud Server version
> 
> 34
> 
> \### 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?
> 
> None
> 
> \### What user-backends are you using?
> 
> \- \[x\] Default user-backend \_(database)\_
> \- \[\] LDAP/ Active Directory
> \- \[\] SSO - SAML
> \- \[\] Other
> 
> \### Configuration report
> 
> \`\`\`json
> {
> "system": {
> "serverid": "1",
> "instanceid": "\*\*\*REMOVED SENSITIVE VALUE\*\*\*",
> "passwordsalt": "\*\*\*REMOVED SENSITIVE VALUE\*\*\*",
> "secret": "\*\*\*REMOVED SENSITIVE VALUE\*\*\*",
> "allow\_local\_remote\_servers": true,
> "trusted\_domains": \[
> "//example.com",
> "//example.com",
> "localhost",
> "//example.com",
> "localhost",
> "//example.com"
> \],
> "trusted\_proxies": "\*\*\*REMOVED SENSITIVE VALUE\*\*\*",
> "push\_server\_url": "https:\\//example.com/push",
> "datadirectory": "\*\*\*REMOVED SENSITIVE VALUE\*\*\*",
> "dbtype": "mysql",
> "version": "34.0.3.2",
> "overwrite.cli.url": "https://example.com",
> "dbname": "\*\*\*REMOVED SENSITIVE VALUE\*\*\*",
> "dbhost": "\*\*\*REMOVED SENSITIVE VALUE\*\*\*",
> "dbport": "",
> "dbtableprefix": "oc\_",
> "mysql.utf8mb4": true,
> "dbuser": "\*\*\*REMOVED SENSITIVE VALUE\*\*\*",
> "dbpassword": "\*\*\*REMOVED SENSITIVE VALUE\*\*\*",
> "installed": true,
> "maintenance": false,
> "memcache.local": "\\\\OC\\\\Memcache\\\\APCu",
> "memcache.distributed": "\\\\OC\\\\Memcache\\\\Redis",
> "redis": {
> "host": "\*\*\*REMOVED SENSITIVE VALUE\*\*\*",
> "port": 6379
> },
> "memcache.locking": "\\\\OC\\\\Memcache\\\\Redis",
> "theme": "",
> "loglevel": 2,
> "overwriteprotocol": "https",
> "mail\_smtpmode": "smtp",
> "mail\_sendmailmode": "smtp",
> "mail\_from\_address": "\*\*\*REMOVED SENSITIVE VALUE\*\*\*",
> "mail\_domain": "\*\*\*REMOVED SENSITIVE VALUE\*\*\*",
> "mail\_smtphost": "\*\*\*REMOVED SENSITIVE VALUE\*\*\*",
> "mail\_smtpport": "587",
> "default\_locale": "ru\_RU",
> "default\_phone\_region": "RU",
> "app\_install\_overwrite": {
> "0": "documentserver\_community",
> "2": "files\_rightclick",
> "3": "metadata",
> "4": "files\_archive"
> },
> "enable\_previews": true,
> "preview\_libreoffice\_path": "\\/usr\\/bin\\/libreoffice",
> "enabledPreviewProviders": \[
> "OC\\\\Preview\\\\TXT",
> "OC\\\\Preview\\\\MarkDown",
> "OC\\\\Preview\\\\OpenDocument",
> "OC\\\\Preview\\\\PDF",
> "OC\\\\Preview\\\\MSOffice2003",
> "OC\\\\Preview\\\\MSOfficeDoc",
> "OC\\\\Preview\\\\MSOffice2007",
> "OC\\\\Preview\\\\Image",
> "OC\\\\Preview\\\\Photoshop",
> "OC\\\\Preview\\\\TIFF",
> "OC\\\\Preview\\\\SVG",
> "OC\\\\Preview\\\\Font",
> "OC\\\\Preview\\\\MP3",
> "OC\\\\Preview\\\\Movie",
> "OC\\\\Preview\\\\MKV",
> "OC\\\\Preview\\\\MP4",
> "OC\\\\Preview\\\\AVI"
> \],
> "apps\_paths": \[
> {
> "path": "\\/var\\/www\\/html\\/nextcloud\\/apps",
> "url": "\\/apps",
> "writable": false
> },
> {
> "path": "\\/var\\/www\\/html\\/nextcloud\\/custom\_apps",
> "url": "\\/custom\_apps",
> "writable": true
> }
> \],
> "mail\_smtpauth": true,
> "mail\_smtpname": "\*\*\*REMOVED SENSITIVE VALUE\*\*\*",
> "mail\_smtppassword": "\*\*\*REMOVED SENSITIVE VALUE\*\*\*",
> "maintenance\_window\_start": 22,
> "collabora\\/code": "https:\\//example.com",
> "fileuploadnew.chunk\_size": "1G",
> "fileuploadnew.max\_filesize": "25G",
> "memory\_limit": "26G",
> "timeout": 36000,
> "enable\_push": true,
> "has\_internet\_connection": true,
> "notify\_push\_base\_endpoint": "https://example.com\\/push",
> "overwritewebroot": "",
> "mail\_smtpauthtype": "LOGIN",
> "mail\_smtpstreamoptions": {
> "ssl": {
> "allow\_self\_signed": false,
> "verify\_peer": true,
> "verify\_peer\_name": true
> }
> },
> "logtimezone": "Europe\\/Moscow",
> "mail\_smtptimeout": 60
> }
> }
> \`\`\`
> 
> \### List of activated Apps
> 
> \`\`\`shell
> Enabled:
> - activity: 7.0.0
> - admin\_audit: 1.24.0
> - admincockpit: 1.3.4
> - analytics: 6.7.1
> - announcementbanner: 2.4.3
> - appstore: 1.0.0
> - bruteforcesettings: 7.0.0
> - calendar: 6.5.3
> - cloud\_federation\_api: 1.18.0
> - comments: 1.24.0
> - contacts: 8.7.6
> - contactsinteraction: 1.15.0
> - dashboard: 7.14.0
> - dav: 1.40.0
> - deck: 1.18.3
> - external: 9.0.1
> - federatedfilesharing: 1.24.0
> - federation: 1.24.0
> - files: 2.6.0
> - files\_accesscontrol: 5.0.0
> - files\_automatedtagging: 5.0.0
> - files\_downloadlimit: 5.2.0
> - files\_external: 1.26.0
> - files\_lock: 34.0.1
> - files\_pdfviewer: 7.0.0-dev.0
> - files\_reminders: 1.7.0
> - files\_retention: 5.0.0
> - files\_sharing: 1.26.0
> - files\_trashbin: 1.24.0
> - files\_versions: 1.27.0
> - flow\_notifications: 5.0.0
> - forms: 5.3.5
> - guests: 4.9.0
> - localpdf: 1.0.0
> - logcleaner: 1.5.6
> - logreader: 7.0.0
> - lookup\_server\_connector: 1.22.0
> - nextcloud\_announcements: 6.0.0
> - notes: 6.0.1
> - notifications: 7.0.0-dev.1
> - notify\_push: 1.4.0
> - oauth2: 1.22.0
> - office: 1.0.0
> - onlyoffice: 10.1.2
> - password\_policy: 6.0.0-dev.0
> - previewgenerator: 5.14.0
> - privacy: 6.0.0-dev.1
> - profile: 1.3.0
> - provisioning\_api: 1.24.0
> - recommendations: 7.0.0
> - related\_resources: 5.0.0-dev.0
> - serverinfo: 6.0.0
> - settings: 1.17.0
> - sharebymail: 1.24.0
> - spreed: 24.0.4
> - support: 6.0.0
> - survey\_client: 6.0.0-dev.0
> - systemtags: 1.24.0
> - tables: 2.2.1
> - tasks: 0.18.1
> - text: 8.0.0
> - theming: 2.9.0
> - thesearchpage: 2.4.3
> - twofactor\_backupcodes: 1.23.0
> - twofactor\_totp: 16.0.0
> - updatenotification: 1.24.0
> - user\_status: 1.14.0
> - viewer: 7.0.0-dev.0
> - weather\_status: 1.14.0
> - webhook\_listeners: 1.6.0
> - workflow\_script: 5.0.0
> - workflowengine: 2.16.0
> Disabled:
> - app\_api: 34.0.0 (installed 32.0.0)
> - circles: 34.0.0 (installed 28.0.0)
> - encryption: 2.22.0
> - files\_archive: 1.2.8 (installed 1.2.8)
> - files\_zip: 3.0.0 (installed 3.0.0)
> - firstrunwizard: 7.0.0-dev.0 (installed 2.18.0)
> - metadata: 0.24.0 (installed 0.24.0)
> - photos: 7.0.0 (installed 2.4.0)
> - side\_menu: 6.0.1 (installed 6.0.1)
> - socialsharing\_email: 4.1.0 (installed 4.1.0)
> - socialsharing\_telegram: 4.1.0 (installed 4.1.0)
> - suspicious\_login: 12.0.0-dev.0
> - testing: 1.23.0
> - twofactor\_nextcloud\_notification: 8.0.0
> - user\_ldap: 1.25.0
> \`\`\`
> 
> \### Nextcloud Signing status
> 
> \`\`\`shell
> 
> \`\`\`
> 
> \### Nextcloud Logs
> 
> \`\`\`json
> \<details\>
> 
> {
> "reqId": "Nrd5F8ZlSxmeEMhpV3fM",
> "level": 3,
> "time": "2026-08-13T21:35:04+03:00",
> "app": "core",
> "message": "Error while running background job OCA\\\\PreviewGenerator\\\\BackgroundJob\\\\PreviewJob (id: 16785, arguments: null)",
> "version": "34.0.3.2",
> "exception": {
> "Exception": "OC\\\\DB\\\\Exceptions\\\\DbalException",
> "Message": "An exception occurred while executing a query: SQLSTATE\[23000\]: Integrity constraint violation: 1052 Column 'file\_id' in WHERE is ambiguous",
> "Code": 1052,
> "Trace": \[
> { "file": ".../lib/private/Preview/Db/PreviewMapper.php", "line": 250, "function": "findEntity", "class": "OCP\\\\AppFramework\\\\Db\\\\QBMapper" },
> { "file": ".../lib/private/Preview/Generator.php", "line": 605, "function": "getPreviewForSpecification", "class": "OC\\\\Preview\\\\Db\\\\PreviewMapper" },
> { "file": ".../lib/private/Preview/Generator.php", "line": 566, "function": "savePreview", "class": "OC\\\\Preview\\\\Generator" },
> { "file": ".../lib/private/Preview/Generator.php", "line": 184, "function": "generatePreview", "class": "OC\\\\Preview\\\\Generator" },
> { "file": ".../lib/private/PreviewManager.php", "line": 203, "function": "generatePreviews", "class": "OC\\\\Preview\\\\Generator" },
> { "file": ".../apps/previewgenerator/lib/Service/PreGenerateService.php", "line": 160, "function": "generatePreviews", "class": "OC\\\\PreviewManager" }
> \],
> "Previous": {
> "Exception": "Doctrine\\\\DBAL\\\\Exception\\\\NonUniqueFieldNameException",
> "Message": "An exception occurred while executing a query: SQLSTATE\[23000\]: Integrity constraint violation: 1052 Column 'file\_id' in WHERE is ambiguous",
> "Code": 1052
> }
> }
> }
> 
> 
> \</details\>
> \`\`\`
> 
> \### Additional info
> 
> The bug does not reproduce on PostgreSQL/SQLite in the same way only if those engines resolve the ambiguity differently; on MySQL/MariaDB it fails consistently on every preview save. Happy to submit a PR with the fix above if maintainers agree with the approach.