[Bug]: An exception occurred while executing a query: SQLSTATE[HY000]: General error: 1205 Lock wait timeout exceeded; try restarting transaction

⚠️ This issue respects the following points: ⚠️

• This is a bug, not a question or a configuration/webserver/proxy issue.
• This issue is not already reported on Github OR Nextcloud Community Forum (I've searched it).
• Nextcloud Server is up to date. See Maintenance and Release Schedule for supported versions.
• I agree to follow Nextcloud's Code of Conduct.

Bug description

Server locking up seeing alot of errors. Just updated to NC 33.0.0 RC2 from NC 32. Looks like is has something to do with previewing. I know something was changed with previewing with this server version.

Steps to reproduce

1.Updated to NC 33.0.0 RC2
2.
3.

Expected behavior

Should not see these error and DB lockup

Nextcloud Server version

33

Operating system

Debian/Ubuntu

PHP engine version

PHP 8.4

Web server

Apache (supported)

Database engine version

MariaDB

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

Upgraded to a MAJOR version (ex. 31 to 32)

Are you using the Nextcloud Server Encryption module?

Encryption is Disabled

What user-backends are you using?

• Default user-backend (database)
• LDAP/ Active Directory
• SSO - SAML
• Other

Configuration report

"system": {
        "instanceid": "***REMOVED SENSITIVE VALUE***",
        "passwordsalt": "***REMOVED SENSITIVE VALUE***",
        "secret": "***REMOVED SENSITIVE VALUE***",
        "serverid": 1,
        "trusted_domains": [
            "***REMOVED SENSITIVE VALUE***",
            "***REMOVED SENSITIVE VALUE***"
        ],
        "datadirectory": "***REMOVED SENSITIVE VALUE***",
        "dbtype": "mysql",
        "version": "33.0.0.13",
        "overwrite.cli.url": "***REMOVED SENSITIVE VALUE***",
        "htaccess.RewriteBase": "\/",
        "dbname": "***REMOVED SENSITIVE VALUE***",
        "dbhost": "***REMOVED SENSITIVE VALUE***",
        "dbport": "",
        "dbtableprefix": "oc_",
        "mysql.utf8mb4": true,
        "dbuser": "***REMOVED SENSITIVE VALUE***",
        "dbpassword": "***REMOVED SENSITIVE VALUE***",
        "installed": true,
        "skeletondirectory": "",
        "maintenance": false,
        "maintenance_window_start": 1,
        "default_phone_region": "US",
        "default_locale": "en_US",
        "memcache.local": "\\OC\\Memcache\\APCu",
        "memcache.distributed": "\\OC\\Memcache\\Redis",
        "memcache.locking": "\\OC\\Memcache\\Redis",
        "redis": {
            "host": "***REMOVED SENSITIVE VALUE***",
            "port": 0,
            "dbindex": 0,
            "password": "***REMOVED SENSITIVE VALUE***",
            "timeout": 1.5
        },
        "trusted_proxies": "***REMOVED SENSITIVE VALUE***",
        "allow_local_remote_servers": true,
        "mail_from_address": "***REMOVED SENSITIVE VALUE***",
        "mail_smtpmode": "smtp",
        "mail_sendmailmode": "smtp",
        "mail_domain": "***REMOVED SENSITIVE VALUE***",
        "mail_smtpport": "587",
        "mail_smtphost": "***REMOVED SENSITIVE VALUE***",
        "enable_previews": true,
        "enabledPreviewProviders": [
            "OC\\Preview\\Image",
            "OC\\Preview\\HEIC",
            "OC\\Preview\\Movie",
            "OC\\Preview\\TIFF",
            "OC\\Preview\\OpenDocument",
            "OC\\Preview\\MSOfficeDoc",
            "OC\\Preview\\SVG",
            "OC\\Preview\\TXT",
            "OC\\Preview\\PNG",
            "OC\\Preview\\PNG"
        ],
        "preview_max_x": 8192,
        "preview_max_y": 8192,
        "defaultapp": "",
        "preview_max_memory": 512,
        "updater.release.channel": "beta",
        "theme": "",
        "loglevel": 2,
        "log.condition": {
            "apps": [
                "admin_audit"
            ]
        },
        "mail_smtpauth": true,
        "mail_smtpname": "***REMOVED SENSITIVE VALUE***",
        "mail_smtppassword": "***REMOVED SENSITIVE VALUE***",
        "twofactor_enforced": "true",
        "twofactor_enforced_groups": [],
        "twofactor_enforced_excluded_groups": [],
        "config_preset": 0,
        "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",
        "memories.vod.ffmpeg": "\/usr\/bin\/ffmpeg",
        "memories.vod.ffprobe": "\/usr\/bin\/ffprobe",
        "memories.gis_type": 1,
        "preview_max_filesize_image": 100,
        "versions_retention_obligation": "7,8",
        "updater.secret": "***REMOVED SENSITIVE VALUE***"
    }
}

List of activated Apps

Enabled:
  - activity: 6.0.0-dev.0
  - admin_audit: 1.23.0
  - approve_links: 1.3.0
  - bruteforcesettings: 6.0.0-dev.0
  - cloud_federation_api: 1.17.0
  - comments: 1.23.0
  - contactsinteraction: 1.14.1
  - dashboard: 7.13.0
  - dav: 1.36.0
  - federatedfilesharing: 1.23.0
  - federation: 1.23.0
  - files: 2.5.0
  - files_accesscontrol: 4.0.0
  - files_automatedtagging: 4.0.0
  - files_confidential: 4.0.0
  - files_downloadlimit: 5.1.0-dev.0
  - files_external: 1.25.1
  - files_pdfviewer: 6.0.0-dev.0
  - files_reminders: 1.6.0
  - files_sharing: 1.25.2
  - files_trashbin: 1.23.0
  - files_versions: 1.26.0
  - firstrunwizard: 6.0.0-dev.0
  - flow_notifications: 4.0.0
  - groupfolders: 21.0.2
  - guests: 4.6.0
  - impersonate: 4.0.0
  - logreader: 6.0.0
  - lookup_server_connector: 1.21.0
  - nextcloud_announcements: 5.0.0
  - notifications: 6.0.0
  - notify_push: 1.3.0
  - oauth2: 1.21.0
  - password_policy: 5.0.0-dev.0
  - photos: 6.0.0-dev.0
  - previewgenerator: 5.12.0-beta.2
  - privacy: 5.0.0-dev.0
  - profile: 1.2.0
  - provisioning_api: 1.23.0
  - quota_warning: 1.23.0
  - recognize: 11.0.1
  - recommendations: 6.0.0-dev.0
  - related_resources: 4.0.0-dev.0
  - richdocuments: 10.0.0-beta.1
  - serverinfo: 5.0.0-dev.0
  - settings: 1.16.0
  - sharebymail: 1.23.0
  - socialsharing_email: 4.0.1
  - spreed: 23.0.0-rc.2
  - support: 5.0.0
  - survey_client: 5.0.0-dev.0
  - suspicious_login: 11.0.0-dev.0
  - systemtags: 1.23.0
  - text: 7.0.0-dev.3
  - theming: 2.8.0
  - theming_customcss: 1.19.0
  - twofactor_backupcodes: 1.22.0
  - twofactor_email: 3.0.6-beta.1
  - twofactor_nextcloud_notification: 7.0.0
  - twofactor_totp: 15.0.0-dev.0
  - twofactor_webauthn: 2.5.0-beta.1
  - updatenotification: 1.23.0
  - user_status: 1.13.0
  - viewer: 6.0.0-dev.0
  - weather_status: 1.13.0
  - webhook_listeners: 1.5.0
  - workflow_pdf_converter: 4.0.0
  - workflowengine: 2.15.0
Disabled:
  - app_api: 33.0.0 (installed 32.0.0)
  - circles: 33.0.0-dev.0 (installed 31.0.0)
  - encryption: 2.21.0
  - files_downloadactivity: 1.18.1 (installed 1.18.1)
  - memories: 7.8.2 (installed 7.8.2)
  - twofactor_admin: 4.9.0 (installed 4.9.0)
  - user_ldap: 1.24.0

Nextcloud Signing status

Nextcloud Logs

{"reqId":"KYYgEmKmNGxCtdN72etk","level":3,"time":"2026-02-04T14:46:40+00:00","remoteAddr":"ip","user":"username","app":"index","method":"GET","url":"/apps/photos/api/v1/preview/3315568?etag=260011eaf3cfd15898c29114f24e4752&x=1024&y=1024","scriptName":"/index.php","message":"An exception occurred while executing a query: SQLSTATE[HY000]: General error: 1205 Lock wait timeout exceeded; try restarting transaction","userAgent":"Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/144.0.0.0 Safari/537.36","version":"33.0.0.13","exception":{"Exception":"OC\\DB\\Exceptions\\DbalException","Message":"An exception occurred while executing a query: SQLSTATE[HY000]: General error: 1205 Lock wait timeout exceeded; try restarting transaction","Code":1205,"Trace":[{"file":"/var/www/nextcloud/lib/private/DB/ConnectionAdapter.php","line":69,"function":"wrap","class":"OC\\DB\\Exceptions\\DbalException","type":"::"},{"file":"/var/www/nextcloud/lib/private/DB/QueryBuilder/QueryBuilder.php","line":283,"function":"executeStatement","class":"OC\\DB\\ConnectionAdapter","type":"->"},{"file":"/var/www/nextcloud/lib/private/Preview/PreviewMigrationService.php","line":170,"function":"executeStatement","class":"OC\\DB\\QueryBuilder\\QueryBuilder","type":"->"},{"file":"/var/www/nextcloud/lib/private/Preview/PreviewMigrationService.php","line":149,"function":"deleteFolder","class":"OC\\Preview\\PreviewMigrationService","type":"->"},{"file":"/var/www/nextcloud/lib/private/Preview/Generator.php","line":212,"function":"migrateFileId","class":"OC\\Preview\\PreviewMigrationService","type":"->"},{"file":"/var/www/nextcloud/lib/private/Preview/Generator.php","line":116,"function":"migrateOldPreviews","class":"OC\\Preview\\Generator","type":"->"},{"file":"/var/www/nextcloud/lib/private/Preview/Generator.php","line":93,"function":"generatePreviews","class":"OC\\Preview\\Generator","type":"->"},{"file":"/var/www/nextcloud/lib/private/PreviewManager.php","line":166,"function":"getPreview","class":"OC\\Preview\\Generator","type":"->"},{"file":"/var/www/nextcloud/apps/photos/lib/Controller/PreviewController.php","line":161,"function":"getPreview","class":"OC\\PreviewManager","type":"->"},{"file":"/var/www/nextcloud/apps/photos/lib/Controller/PreviewController.php","line":118,"function":"fetchPreview","class":"OCA\\Photos\\Controller\\PreviewController","type":"->"},{"file":"/var/www/nextcloud/lib/private/AppFramework/Http/Dispatcher.php","line":205,"function":"index","class":"OCA\\Photos\\Controller\\PreviewController","type":"->"},{"file":"/var/www/nextcloud/lib/private/AppFramework/Http/Dispatcher.php","line":118,"function":"executeController","class":"OC\\AppFramework\\Http\\Dispatcher","type":"->"},{"file":"/var/www/nextcloud/lib/private/AppFramework/App.php","line":153,"function":"dispatch","class":"OC\\AppFramework\\Http\\Dispatcher","type":"->"},{"file":"/var/www/nextcloud/lib/private/Route/Router.php","line":321,"function":"main","class":"OC\\AppFramework\\App","type":"::"},{"file":"/var/www/nextcloud/lib/base.php","line":1155,"function":"match","class":"OC\\Route\\Router","type":"->"},{"file":"/var/www/nextcloud/index.php","line":25,"function":"handleRequest","class":"OC","type":"::"}],"File":"/var/www/nextcloud/lib/private/DB/Exceptions/DbalException.php","Line":56,"Previous":{"Exception":"Doctrine\\DBAL\\Exception\\LockWaitTimeoutException","Message":"An exception occurred while executing a query: SQLSTATE[HY000]: General error: 1205 Lock wait timeout exceeded; try restarting transaction","Code":1205,"Trace":[{"file":"/var/www/nextcloud/3rdparty/doctrine/dbal/src/Connection.php","line":1976,"function":"convert","class":"Doctrine\\DBAL\\Driver\\API\\MySQL\\ExceptionConverter","type":"->"},{"file":"/var/www/nextcloud/3rdparty/doctrine/dbal/src/Connection.php","line":1918,"function":"handleDriverException","class":"Doctrine\\DBAL\\Connection","type":"->"},{"file":"/var/www/nextcloud/3rdparty/doctrine/dbal/src/Connection.php","line":1218,"function":"convertExceptionDuringQuery","class":"Doctrine\\DBAL\\Connection","type":"->"},{"file":"/var/www/nextcloud/3rdparty/doctrine/dbal/src/Connections/PrimaryReadReplicaConnection.php","line":292,"function":"executeStatement","class":"Doctrine\\DBAL\\Connection","type":"->"},{"file":"/var/www/nextcloud/lib/private/DB/Connection.php","line":467,"function":"executeStatement","class":"Doctrine\\DBAL\\Connections\\PrimaryReadReplicaConnection","type":"->"},{"file":"/var/www/nextcloud/lib/private/DB/ConnectionAdapter.php","line":67,"function":"executeStatement","class":"OC\\DB\\Connection","type":"->"},{"file":"/var/www/nextcloud/lib/private/DB/QueryBuilder/QueryBuilder.php","line":283,"function":"executeStatement","class":"OC\\DB\\ConnectionAdapter","type":"->"},{"file":"/var/www/nextcloud/lib/private/Preview/PreviewMigrationService.php","line":170,"function":"executeStatement","class":"OC\\DB\\QueryBuilder\\QueryBuilder","type":"->"},{"file":"/var/www/nextcloud/lib/private/Preview/PreviewMigrationService.php","line":149,"function":"deleteFolder","class":"OC\\Preview\\PreviewMigrationService","type":"->"},{"file":"/var/www/nextcloud/lib/private/Preview/Generator.php","line":212,"function":"migrateFileId","class":"OC\\Preview\\PreviewMigrationService","type":"->"},{"file":"/var/www/nextcloud/lib/private/Preview/Generator.php","line":116,"function":"migrateOldPreviews","class":"OC\\Preview\\Generator","type":"->"},{"file":"/var/www/nextcloud/lib/private/Preview/Generator.php","line":93,"function":"generatePreviews","class":"OC\\Preview\\Generator","type":"->"},{"file":"/var/www/nextcloud/lib/private/PreviewManager.php","line":166,"function":"getPreview","class":"OC\\Preview\\Generator","type":"->"},{"file":"/var/www/nextcloud/apps/photos/lib/Controller/PreviewController.php","line":161,"function":"getPreview","class":"OC\\PreviewManager","type":"->"},{"file":"/var/www/nextcloud/apps/photos/lib/Controller/PreviewController.php","line":118,"function":"fetchPreview","class":"OCA\\Photos\\Controller\\PreviewController","type":"->"},{"file":"/var/www/nextcloud/lib/private/AppFramework/Http/Dispatcher.php","line":205,"function":"index","class":"OCA\\Photos\\Controller\\PreviewController","type":"->"},{"file":"/var/www/nextcloud/lib/private/AppFramework/Http/Dispatcher.php","line":118,"function":"executeController","class":"OC\\AppFramework\\Http\\Dispatcher","type":"->"},{"file":"/var/www/nextcloud/lib/private/AppFramework/App.php","line":153,"function":"dispatch","class":"OC\\AppFramework\\Http\\Dispatcher","type":"->"},{"file":"/var/www/nextcloud/lib/private/Route/Router.php","line":321,"function":"main","class":"OC\\AppFramework\\App","type":"::"},{"file":"/var/www/nextcloud/lib/base.php","line":1155,"function":"match","class":"OC\\Route\\Router","type":"->"},{"file":"/var/www/nextcloud/index.php","line":25,"function":"handleRequest","class":"OC","type":"::"}],"File":"/var/www/nextcloud/3rdparty/doctrine/dbal/src/Driver/API/MySQL/ExceptionConverter.php","Line":44,"Previous":{"Exception":"Doctrine\\DBAL\\Driver\\PDO\\Exception","Message":"SQLSTATE[HY000]: General error: 1205 Lock wait timeout exceeded; try restarting transaction","Code":1205,"Trace":[{"file":"/var/www/nextcloud/3rdparty/doctrine/dbal/src/Driver/PDO/Statement.php","line":132,"function":"new","class":"Doctrine\\DBAL\\Driver\\PDO\\Exception","type":"::"},{"file":"/var/www/nextcloud/3rdparty/doctrine/dbal/src/Connection.php","line":1212,"function":"execute","class":"Doctrine\\DBAL\\Driver\\PDO\\Statement","type":"->"},{"file":"/var/www/nextcloud/3rdparty/doctrine/dbal/src/Connections/PrimaryReadReplicaConnection.php","line":292,"function":"executeStatement","class":"Doctrine\\DBAL\\Connection","type":"->"},{"file":"/var/www/nextcloud/lib/private/DB/Connection.php","line":467,"function":"executeStatement","class":"Doctrine\\DBAL\\Connections\\PrimaryReadReplicaConnection","type":"->"},{"file":"/var/www/nextcloud/lib/private/DB/ConnectionAdapter.php","line":67,"function":"executeStatement","class":"OC\\DB\\Connection","type":"->"},{"file":"/var/www/nextcloud/lib/private/DB/QueryBuilder/QueryBuilder.php","line":283,"function":"executeStatement","class":"OC\\DB\\ConnectionAdapter","type":"->"},{"file":"/var/www/nextcloud/lib/private/Preview/PreviewMigrationService.php","line":170,"function":"executeStatement","class":"OC\\DB\\QueryBuilder\\QueryBuilder","type":"->"},{"file":"/var/www/nextcloud/lib/private/Preview/PreviewMigrationService.php","line":149,"function":"deleteFolder","class":"OC\\Preview\\PreviewMigrationService","type":"->"},{"file":"/var/www/nextcloud/lib/private/Preview/Generator.php","line":212,"function":"migrateFileId","class":"OC\\Preview\\PreviewMigrationService","type":"->"},{"file":"/var/www/nextcloud/lib/private/Preview/Generator.php","line":116,"function":"migrateOldPreviews","class":"OC\\Preview\\Generator","type":"->"},{"file":"/var/www/nextcloud/lib/private/Preview/Generator.php","line":93,"function":"generatePreviews","class":"OC\\Preview\\Generator","type":"->"},{"file":"/var/www/nextcloud/lib/private/PreviewManager.php","line":166,"function":"getPreview","class":"OC\\Preview\\Generator","type":"->"},{"file":"/var/www/nextcloud/apps/photos/lib/Controller/PreviewController.php","line":161,"function":"getPreview","class":"OC\\PreviewManager","type":"->"},{"file":"/var/www/nextcloud/apps/photos/lib/Controller/PreviewController.php","line":118,"function":"fetchPreview","class":"OCA\\Photos\\Controller\\PreviewController","type":"->"},{"file":"/var/www/nextcloud/lib/private/AppFramework/Http/Dispatcher.php","line":205,"function":"index","class":"OCA\\Photos\\Controller\\PreviewController","type":"->"},{"file":"/var/www/nextcloud/lib/private/AppFramework/Http/Dispatcher.php","line":118,"function":"executeController","class":"OC\\AppFramework\\Http\\Dispatcher","type":"->"},{"file":"/var/www/nextcloud/lib/private/AppFramework/App.php","line":153,"function":"dispatch","class":"OC\\AppFramework\\Http\\Dispatcher","type":"->"},{"file":"/var/www/nextcloud/lib/private/Route/Router.php","line":321,"function":"main","class":"OC\\AppFramework\\App","type":"::"},{"file":"/var/www/nextcloud/lib/base.php","line":1155,"function":"match","class":"OC\\Route\\Router","type":"->"},{"file":"/var/www/nextcloud/index.php","line":25,"function":"handleRequest","class":"OC","type":"::"}],"File":"/var/www/nextcloud/3rdparty/doctrine/dbal/src/Driver/PDO/Exception.php","Line":24,"Previous":{"Exception":"PDOException","Message":"SQLSTATE[HY000]: General error: 1205 Lock wait timeout exceeded; try restarting transaction","Code":"HY000","Trace":[{"file":"/var/www/nextcloud/3rdparty/doctrine/dbal/src/Driver/PDO/Statement.php","line":130,"function":"execute","class":"PDOStatement","type":"->"},{"file":"/var/www/nextcloud/3rdparty/doctrine/dbal/src/Connection.php","line":1212,"function":"execute","class":"Doctrine\\DBAL\\Driver\\PDO\\Statement","type":"->"},{"file":"/var/www/nextcloud/3rdparty/doctrine/dbal/src/Connections/PrimaryReadReplicaConnection.php","line":292,"function":"executeStatement","class":"Doctrine\\DBAL\\Connection","type":"->"},{"file":"/var/www/nextcloud/lib/private/DB/Connection.php","line":467,"function":"executeStatement","class":"Doctrine\\DBAL\\Connections\\PrimaryReadReplicaConnection","type":"->"},{"file":"/var/www/nextcloud/lib/private/DB/ConnectionAdapter.php","line":67,"function":"executeStatement","class":"OC\\DB\\Connection","type":"->"},{"file":"/var/www/nextcloud/lib/private/DB/QueryBuilder/QueryBuilder.php","line":283,"function":"executeStatement","class":"OC\\DB\\ConnectionAdapter","type":"->"},{"file":"/var/www/nextcloud/lib/private/Preview/PreviewMigrationService.php","line":170,"function":"executeStatement","class":"OC\\DB\\QueryBuilder\\QueryBuilder","type":"->"},{"file":"/var/www/nextcloud/lib/private/Preview/PreviewMigrationService.php","line":149,"function":"deleteFolder","class":"OC\\Preview\\PreviewMigrationService","type":"->"},{"file":"/var/www/nextcloud/lib/private/Preview/Generator.php","line":212,"function":"migrateFileId","class":"OC\\Preview\\PreviewMigrationService","type":"->"},{"file":"/var/www/nextcloud/lib/private/Preview/Generator.php","line":116,"function":"migrateOldPreviews","class":"OC\\Preview\\Generator","type":"->"},{"file":"/var/www/nextcloud/lib/private/Preview/Generator.php","line":93,"function":"generatePreviews","class":"OC\\Preview\\Generator","type":"->"},{"file":"/var/www/nextcloud/lib/private/PreviewManager.php","line":166,"function":"getPreview","class":"OC\\Preview\\Generator","type":"->"},{"file":"/var/www/nextcloud/apps/photos/lib/Controller/PreviewController.php","line":161,"function":"getPreview","class":"OC\\PreviewManager","type":"->"},{"file":"/var/www/nextcloud/apps/photos/lib/Controller/PreviewController.php","line":118,"function":"fetchPreview","class":"OCA\\Photos\\Controller\\PreviewController","type":"->"},{"file":"/var/www/nextcloud/lib/private/AppFramework/Http/Dispatcher.php","line":205,"function":"index","class":"OCA\\Photos\\Controller\\PreviewController","type":"->"},{"file":"/var/www/nextcloud/lib/private/AppFramework/Http/Dispatcher.php","line":118,"function":"executeController","class":"OC\\AppFramework\\Http\\Dispatcher","type":"->"},{"file":"/var/www/nextcloud/lib/private/AppFramework/App.php","line":153,"function":"dispatch","class":"OC\\AppFramework\\Http\\Dispatcher","type":"->"},{"file":"/var/www/nextcloud/lib/private/Route/Router.php","line":321,"function":"main","class":"OC\\AppFramework\\App","type":"::"},{"file":"/var/www/nextcloud/lib/base.php","line":1155,"function":"match","class":"OC\\Route\\Router","type":"->"},{"file":"/var/www/nextcloud/index.php","line":25,"function":"handleRequest","class":"OC","type":"::"}],"File":"/var/www/nextcloud/3rdparty/doctrine/dbal/src/Driver/PDO/Statement.php","Line":130}}},"message":"An exception occurred while executing a query: SQLSTATE[HY000]: General error: 1205 Lock wait timeout exceeded; try restarting transaction","exception":"{\"class\":\"OC\\DB\\Exceptions\\DbalException\",\"message\":\"An exception occurred while executing a query: SQLSTATE[HY000]: General error: 1205 Lock wait timeout exceeded; try restarting transaction\",\"code\":1205,\"file\":\"/var/www/nextcloud/lib/private/DB/Exceptions/DbalException.php:56\",\"trace\":\"#0 /var/www/nextcloud/lib/private/DB/ConnectionAdapter.php(69): OC\\DB\\Exceptions\\DbalException::wrap()\\n#1 /var/www/nextcloud/lib/private/DB/QueryBuilder/QueryBuilder.php(283): OC\\DB\\ConnectionAdapter->executeStatement()\\n#2 /var/www/nextcloud/lib/private/Preview/PreviewMigrationService.php(170): OC\\DB\\QueryBuilder\\QueryBuilder->executeStatement()\\n#3 /var/www/nextcloud/lib/private/Preview/PreviewMigrationService.php(149): OC\\Preview\\PreviewMigrationService->deleteFolder()\\n#4 /var/www/nextcloud/lib/private/Preview/Generator.php(212): OC\\Preview\\PreviewMigrationService->migrateFileId()\\n#5 /var/www/nextcloud/lib/private/Preview/Generator.php(116): OC\\Preview\\Generator->migrateOldPreviews()\\n#6 /var/www/nextcloud/lib/private/Preview/Generator.php(93): OC\\Preview\\Generator->generatePreviews()\\n#7 /var/www/nextcloud/lib/private/PreviewManager.php(166): OC\\Preview\\Generator->getPreview()\\n#8 /var/www/nextcloud/apps/photos/lib/Controller/PreviewController.php(161): OC\\PreviewManager->getPreview()\\n#9 /var/www/nextcloud/apps/photos/lib/Controller/PreviewController.php(118): OCA\\Photos\\Controller\\PreviewController->fetchPreview()\\n#10 /var/www/nextcloud/lib/private/AppFramework/Http/Dispatcher.php(205): OCA\\Photos\\Controller\\PreviewController->index()\\n#11 /var/www/nextcloud/lib/private/AppFramework/Http/Dispatcher.php(118): OC\\AppFramework\\Http\\Dispatcher->executeController()\\n#12 /var/www/nextcloud/lib/private/AppFramework/App.php(153): OC\\AppFramework\\Http\\Dispatcher->dispatch()\\n#13 /var/www/nextcloud/lib/private/Route/Router.php(321): OC\\AppFramework\\App::main()\\n#14 /var/www/nextcloud/lib/base.php(1155): OC\\Route\\Router->match()\\n#15 /var/www/nextcloud/index.php(25): OC::handleRequest()\\n#16 {main}\",\"previous\":{\"class\":\"Doctrine\\DBAL\\Exception\\LockWaitTimeoutException\",\"message\":\"An exception occurred while executing a query: SQLSTATE[HY000]: General error: 1205 Lock wait timeout exceeded; try restarting transaction\",\"code\":1205,\"file\":\"/var/www/nextcloud/3rdparty/doctrine/dbal/src/Driver/API/MySQL/ExceptionConverter.php:44\",\"trace\":\"#0 /var/www/nextcloud/3rdparty/doctrine/dbal/src/Connection.php(1976): Doctrine\\DBAL\\Driver\\API\\MySQL\\ExceptionConverter->convert()\\n#1 /var/www/nextcloud/3rdparty/doctrine/dbal/src/Connection.php(1918): Doctrine\\DBAL\\Connection->handleDriverException()\\n#2 /var/www/nextcloud/3rdparty/doctrine/dbal/src/Connection.php(1218): Doctrine\\DBAL\\Connection->convertExceptionDuringQuery()\\n#3 /var/www/nextcloud/3rdparty/doctrine/dbal/src/Connections/PrimaryReadReplicaConnection.php(292): Doctrine\\DBAL\\Connection->executeStatement()\\n#4 /var/www/nextcloud/lib/private/DB/Connection.php(467): Doctrine\\DBAL\\Connections\\PrimaryReadReplicaConnection->executeStatement()\\n#5 /var/www/nextcloud/lib/private/DB/ConnectionAdapter.php(67): OC\\DB\\Connection->executeStatement()\\n#6 /var/www/nextcloud/lib/private/DB/QueryBuilder/QueryBuilder.php(283): OC\\DB\\ConnectionAdapter->executeStatement()\\n#7 /var/www/nextcloud/lib/private/Preview/PreviewMigrationService.php(170): OC\\DB\\QueryBuilder\\QueryBuilder->executeStatement()\\n#8 /var/www/nextcloud/lib/private/Preview/PreviewMigrationService.php(149): OC\\Preview\\PreviewMigrationService->deleteFolder()\\n#9 /var/www/nextcloud/lib/private/Preview/Generator.php(212): OC\\Preview\\PreviewMigrationService->migrateFileId()\\n#10 /var/www/nextcloud/lib/private/Preview/Generator.php(116): OC\\Preview\\Generator->migrateOldPreviews()\\n#11 /var/www/nextcloud/lib/private/Preview/Generator.php(93): OC\\Preview\\Generator->generatePreviews()\\n#12 /var/www/nextcloud/lib/private/PreviewManager.php(166): OC\\Preview\\Generator->getPreview()\\n#13 /var/www/nextcloud/apps/photos/lib/Controller/PreviewController.php(161): OC\\PreviewManager->getPreview()\\n#14 /var/www/nextcloud/apps/photos/lib/Controller/PreviewController.php(118): OCA\\Photos\\Controller\\PreviewController->fetchPreview()\\n#15 /var/www/nextcloud/lib/private/AppFramework/Http/Dispatcher.php(205): OCA\\Photos\\Controller\\PreviewController->index()\\n#16 /var/www/nextcloud/lib/private/AppFramework/Http/Dispatcher.php(118): OC\\AppFramework\\Http\\Dispatcher->executeController()\\n#17 /var/www/nextcloud/lib/private/AppFramework/App.php(153): OC\\AppFramework\\Http\\Dispatcher->dispatch()\\n#18 /var/www/nextcloud/lib/private/Route/Router.php(321): OC\\AppFramework\\App::main()\\n#19 /var/www/nextcloud/lib/base.php(1155): OC\\Route\\Router->match()\\n#20 /var/www/nextcloud/index.php(25): OC::handleRequest()\\n#21 {main}\",\"previous\":{\"class\":\"Doctrine\\DBAL\\Driver\\PDO\\Exception\",\"message\":\"SQLSTATE[HY000]: General error: 1205 Lock wait timeout exceeded; try restarting transaction\",\"code\":1205,\"file\":\"/var/www/nextcloud/3rdparty/doctrine/dbal/src/Driver/PDO/Exception.php:24\",\"trace\":\"#0 /var/www/nextcloud/3rdparty/doctrine/dbal/src/Driver/PDO/Statement.php(132): Doctrine\\DBAL\\Driver\\PDO\\Exception::new()\\n#1 /var/www/nextcloud/3rdparty/doctrine/dbal/src/Connection.php(1212): Doctrine\\DBAL\\Driver\\PDO\\Statement->execute()\\n#2 /var/www/nextcloud/3rdparty/doctrine/dbal/src/Connections/PrimaryReadReplicaConnection.php(292): Doctrine\\DBAL\\Connection->executeStatement()\\n#3 /var/www/nextcloud/lib/private/DB/Connection.php(467): Doctrine\\DBAL\\Connections\\PrimaryReadReplicaConnection->executeStatement()\\n#4 /var/www/nextcloud/lib/private/DB/ConnectionAdapter.php(67): OC\\DB\\Connection->executeStatement()\\n#5 /var/www/nextcloud/lib/private/DB/QueryBuilder/QueryBuilder.php(283): OC\\DB\\ConnectionAdapter->executeStatement()\\n#6 /var/www/nextcloud/lib/private/Preview/PreviewMigrationService.php(170): OC\\DB\\QueryBuilder\\QueryBuilder->executeStatement()\\n#7 /var/www/nextcloud/lib/private/Preview/PreviewMigrationService.php(149): OC\\Preview\\PreviewMigrationService->deleteFolder()\\n#8 /var/www/nextcloud/lib/private/Preview/Generator.php(212): OC\\Preview\\PreviewMigrationService->migrateFileId()\\n#9 /var/www/nextcloud/lib/private/Preview/Generator.php(116): OC\\Preview\\Generator->migrateOldPreviews()\\n#10 /var/www/nextcloud/lib/private/Preview/Generator.php(93): OC\\Preview\\Generator->generatePreviews()\\n#11 /var/www/nextcloud/lib/private/PreviewManager.php(166): OC\\Preview\\Generator->getPreview()\\n#12 /var/www/nextcloud/apps/photos/lib/Controller/PreviewController.php(161): OC\\PreviewManager->getPreview()\\n#13 /var/www/nextcloud/apps/photos/lib/Controller/PreviewController.php(118): OCA\\Photos\\Controller\\PreviewController->fetchPreview()\\n#14 /var/www/nextcloud/lib/private/AppFramework/Http/Dispatcher.php(205): OCA\\Photos\\Controller\\PreviewController->index()\\n#15 /var/www/nextcloud/lib/private/AppFramework/Http/Dispatcher.php(118): OC\\AppFramework\\Http\\Dispatcher->executeController()\\n#16 /var/www/nextcloud/lib/private/AppFramework/App.php(153): OC\\AppFramework\\Http\\Dispatcher->dispatch()\\n#17 /var/www/nextcloud/lib/private/Route/Router.php(321): OC\\AppFramework\\App::main()\\n#18 /var/www/nextcloud/lib/base.php(1155): OC\\Route\\Router->match()\\n#19 /var/www/nextcloud/index.php(25): OC::handleRequest()\\n#20 {main}\",\"previous\":{\"class\":\"PDOException\",\"message\":\"SQLSTATE[HY000]: General error: 1205 Lock wait timeout exceeded; try restarting transaction\",\"code\":\"HY000\",\"file\":\"/var/www/nextcloud/3rdparty/doctrine/dbal/src/Driver/PDO/Statement.php:130\",\"trace\":\"#0 /var/www/nextcloud/3rdparty/doctrine/dbal/src/Driver/PDO/Statement.php(130): PDOStatement->execute()\\n#1 /var/www/nextcloud/3rdparty/doctrine/dbal/src/Connection.php(1212): Doctrine\\DBAL\\Driver\\PDO\\Statement->execute()\\n#2 /var/www/nextcloud/3rdparty/doctrine/dbal/src/Connections/PrimaryReadReplicaConnection.php(292): Doctrine\\DBAL\\Connection->executeStatement()\\n#3 /var/www/nextcloud/lib/private/DB/Connection.php(467): Doctrine\\DBAL\\Connections\\PrimaryReadReplicaConnection->executeStatement()\\n#4 /var/www/nextcloud/lib/private/DB/ConnectionAdapter.php(67): OC\\DB\\Connection->executeStatement()\\n#5 /var/www/nextcloud/lib/private/DB/QueryBuilder/QueryBuilder.php(283): OC\\DB\\ConnectionAdapter->executeStatement()\\n#6 /var/www/nextcloud/lib/private/Preview/PreviewMigrationService.php(170): OC\\DB\\QueryBuilder\\QueryBuilder->executeStatement()\\n#7 /var/www/nextcloud/lib/private/Preview/PreviewMigrationService.php(149): OC\\Preview\\PreviewMigrationService->deleteFolder()\\n#8 /var/www/nextcloud/lib/private/Preview/Generator.php(212): OC\\Preview\\PreviewMigrationService->migrateFileId()\\n#9 /var/www/nextcloud/lib/private/Preview/Generator.php(116): OC\\Preview\\Generator->migrateOldPreviews()\\n#10 /var/www/nextcloud/lib/private/Preview/Generator.php(93): OC\\Preview\\Generator->generatePreviews()\\n#11 /var/www/nextcloud/lib/private/PreviewManager.php(166): OC\\Preview\\Generator->getPreview()\\n#12 /var/www/nextcloud/apps/photos/lib/Controller/PreviewController.php(161): OC\\PreviewManager->getPreview()\\n#13 /var/www/nextcloud/apps/photos/lib/Controller/PreviewController.php(118): OCA\\Photos\\Controller\\PreviewController->fetchPreview()\\n#14 /var/www/nextcloud/lib/private/AppFramework/Http/Dispatcher.php(205): OCA\\Photos\\Controller\\PreviewController->index()\\n#15 /var/www/nextcloud/lib/private/AppFramework/Http/Dispatcher.php(118): OC\\AppFramework\\Http\\Dispatcher->executeController()\\n#16 /var/www/nextcloud/lib/private/AppFramework/App.php(153): OC\\AppFramework\\Http\\Dispatcher->dispatch()\\n#17 /var/www/nextcloud/lib/private/Route/Router.php(321): OC\\AppFramework\\App::main()\\n#18 /var/www/nextcloud/lib/base.php(1155): OC\\Route\\Router->match()\\n#19 /var/www/nextcloud/index.php(25): OC::handleRequest()\\n#20 {main}\"}}}}","CustomMessage":"An exception occurred while executing a query: SQLSTATE[HY000]: General error: 1205 Lock wait timeout exceeded; try restarting transaction"},"id":"69835d27e99fe"}

Additional info

Start with the reported request in apps/photos/lib/Controller/PreviewController.php and follow the preview path through lib/private/Preview/Generator.php and PreviewMigrationService.php. Inspect the query at PreviewMigrationService.php:170 and the accompanying lock-timeout trace. Done means identifying and preventing the MariaDB lock timeout during preview requests, with relevant verification added where the affected behavior is tested.