The Basics
- Nextcloud Server version (e.g., 29.x.x):
34.0.2.1
- Operating system and version (e.g., Ubuntu 24.04):
Ubuntu 26.04
- Web server and version (e.g, Apache 2.4.25):
- nginx 1.28.3-2ubuntu1.8
- Reverse proxy and version _(e.g. nginx 1.27.2)
traefik 3.7.8
- PHP version (e.g, 8.3):
8.5
- Is this the first time you’ve seen this error? (Yes / No):
yes
- When did this problem seem to first start?
? but before updating to 34.0.2.1 (was 33.0.7)
- Installation method (e.g. AlO, NCP, Bare Metal/Archive, etc.)
Bare Metal
- Are you using CloudfIare, mod_security, or similar? (Yes / No)
no
Summary of the issue you are facing:
Once Invitations was sent to the attendees but suddenly they are not sent to the attendees of calendar events. The Calendar server->Send invitations to attendees stays disabled, even if set to enabled. If you refresh the Calendar server page it is shown disabled again.
Because of the warnings in the nextcloud.log (see below) I tried to set the dav/sendInvitations attribute with occ command as type string (=“true”) and boolean(=true) with no luck, even after restarting redis, php, nginx.
Steps to replicate it (hint: details matter!):
-
Setup system mails and test if mails are send
-
in the admin section of calendar server set the attribute “Send invitations to attendees” to “on”.
-
refresh the calendar server admin page. The attribute shows “off” again.
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":"WxaBoHSZmmwwS2Fj2zx6","level":1,"time":"2026-08-06T11:47:21+00:00","remoteAddr":"192.168.3.202","user":"user","app":"no app in context","method":"PROPFIND","url":"/remote.php/dav/files/user/","scriptName":"/remote.php","message":"The app config key dav/enableCalendarFederation is not defined in the config lexicon","userAgent":"Mozilla/5.0 (Macintosh) mirall/34.0.1 (Nextcloud, macos-25.5.0 ClientArchitecture: arm64 OsArchitecture: arm64)","version":"34.0.2.1","clientReqId":"74a81230-a803-448f-9388-9effe478f5e4","data":[]}
{"reqId":"WxaBoHSZmmwwS2Fj2zx6","level":1,"time":"2026-08-06T11:47:21+00:00","remoteAddr":"192.168.3.202","user":"bubi","user":"no app in context","method":"PROPFIND","url":"/remote.php/dav/files/user/","scriptName":"/remote.php","message":"The app config key dav/sendInvitations is not defined in the config lexicon","userAgent":"Mozilla/5.0 (Macintosh) mirall/34.0.1 (Nextcloud, macos-25.5.0 ClientArchitecture: arm64 OsArchitecture: arm64)","version":"34.0.2.1","clientReqId":"74a81230-a803-448f-9388-9effe478f5e4","data":[]}
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.
ERROR] viewer: Could not register handler
Object { app: "viewer", uid: "user", level: 1, error: "The handler is already registered", handler: {…} }
index.mjs:47:17
log index.mjs:47
error index.mjs:65
registerHandler Viewer.js:89
beforeMount Viewer.vue:526
beforeMount Viewer.vue:525
(Async: EventListener.handleEvent)
beforeMount Viewer.vue:522
VueJS 16
<anonym> main.js:32
Web server / Reverse Proxy
The output of your Apache/nginx/system log in /var/log/____:
...
{"reqId":"WxaBoHSZmmwwS2Fj2zx6","level":1,"time":"2026-08-06T11:47:21+00:00","remoteAddr":"192.168.3.202","user":"user","app":"no app in context","method":"PROPFIND","url":"/remote.php/dav/files/user/","scriptName":"/remote.php","message":"The app config key dav/enableCalendarFederation is not defined in the config lexicon","userAgent":"Mozilla/5.0 (Macintosh) mirall/34.0.1 (Nextcloud, macos-25.5.0 ClientArchitecture: arm64 OsArchitecture: arm64)","version":"34.0.2.1","clientReqId":"74a81230-a803-448f-9388-9effe478f5e4","data":[]}
{"reqId":"WxaBoHSZmmwwS2Fj2zx6","level":1,"time":"2026-08-06T11:47:21+00:00","remoteAddr":"192.168.3.202","user":"bubi","user":"no app in context","method":"PROPFIND","url":"/remote.php/dav/files/user/","scriptName":"/remote.php","message":"The app config key dav/sendInvitations is not defined in the config lexicon","userAgent":"Mozilla/5.0 (Macintosh) mirall/34.0.1 (Nextcloud, macos-25.5.0 ClientArchitecture: arm64 OsArchitecture: arm64)","version":"34.0.2.1","clientReqId":"74a81230-a803-448f-9388-9effe478f5e4","data":[]}
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***",
"trusted_proxies": "***REMOVED SENSITIVE VALUE***",
"overwriteprotocol": "https",
"trusted_domains": [
"cloud.example.org"
],
"datadirectory": "***REMOVED SENSITIVE VALUE***",
"dbtype": "mysql",
"version": "34.0.2.1",
"overwrite.cli.url": "https:\/\/cloud.example.org",
"dbname": "***REMOVED SENSITIVE VALUE***",
"dbhost": "***REMOVED SENSITIVE VALUE***",
"dbport": "",
"dbtableprefix": "oc_",
"dbuser": "***REMOVED SENSITIVE VALUE***",
"dbpassword": "***REMOVED SENSITIVE VALUE***",
"installed": true,
"maintenance": false,
"mail_from_address": "***REMOVED SENSITIVE VALUE***",
"mail_smtpmode": "smtp",
"mail_sendmailmode": "smtp",
"mail_domain": "***REMOVED SENSITIVE VALUE***",
"mail_smtpauthtype": "LOGIN",
"mail_smtpauth": true,
"mail_smtphost": "***REMOVED SENSITIVE VALUE***",
"mail_smtpport": "25",
"mail_smtpname": "***REMOVED SENSITIVE VALUE***",
"mail_smtppassword": "***REMOVED SENSITIVE VALUE***",
"theme": "",
"updater.release.channel": "stable",
"mysql.utf8mb4": true,
"app_install_overwrite": {
"0": "files_ebookreader",
"1": "impersonatte",
"4": "epubreader",
"5": "cookbook",
"6": "apporder",
"7": "facerecognition",
"8": "passwords",
"9": "pride",
"10": "camerarawpreviews",
"12": "music",
"13": "radio",
"14": "event_update_notification",
"15": "richdocumentscode",
"16": "maps",
"17": "oidc",
"18": "workflow_media_converter",
"19": "fulltextsearch_elasticsearch",
"20": "fulltextsearch",
"21": "files_fulltextsearch",
"22": "memories",
"23": "side_menu"
},
"enable_previews": true,
"enabledPreviewProviders": [
"OC\\Preview\\Image",
"OC\\Preview\\Movie",
"OC\\Preview\\TXT",
"OC\\Preview\\HEIC",
"OC\\Preview\\JPEG",
"OC\\Preview\\MP3",
"OC\\Preview\\TXT",
"OC\\Preview\\MarkDown",
"OC\\Preview\\OpenDocument",
"OC\\Preview\\Krita",
"OC\\Preview\\PDF"
],
"default_phone_region": "DE",
"loglevel": 1,
"filelocking.enabled": true,
"memcache.local": "\\OC\\Memcache\\Redis",
"memcache.locking": "\\OC\\Memcache\\Redis",
"redis": {
"host": "***REMOVED SENSITIVE VALUE***",
"port": 0,
"timeout": 0
},
"maintenance_window_start": 1,
"memories.db.triggers.fcu": true,
"memories.exiftool": "\/var\/www\/cloud.example.com\/apps\/memories\/bin-ext\/exiftool-amd64-glibc",
"memories.vod.path": "\/var\/www\/cloud.example.com\/apps\/memories\/bin-ext\/go-vod-amd64",
"memories.vod.ffmpeg": "\/usr\/bin\/ffmpeg",
"memories.vod.ffprobe": "\/usr\/bin\/ffprobe",
"preview_max_x": 2048,
"preview_max_y": 2048,
"jpeg_quality": 60,
"memories.vod.disable": false,
"memories.gis_type": 1,
"config_preset": 2,
"enable_lazy_objects": false,
"defaultapp": "dashboard,memories,files",
"mail_smtpstreamoptions": {
"ssl": {
"allow_self_signed": false,
"verify_peer": true,
"verify_peer_name": true
}
},
"dav\/sendInvitations": "true",
"updater.secret": "***REMOVED SENSITIVE VALUE***"
}
}
Apps
The output of occ app:list (if possible).
Enabled:
- activity: 7.0.0
- admin_audit: 1.24.0
- analytics: 6.7.1
- announcementbanner: 2.4.3
- announcementcenter: 7.4.1
- app_api: 34.0.0
- appstore: 1.0.0
- assistant: 3.5.0
- audiocoverpreview: 0.12.1
- bruteforcesettings: 7.0.0
- calendar: 6.5.2
- calendar_resource_management: 0.12.1
- camerarawpreviews: 1.1.2
- circles: 34.0.0
- cloud_federation_api: 1.18.0
- collectives: 4.4.2
- comments: 1.24.0
- contacts: 8.7.5
- contactsinteraction: 1.15.0
- cookbook: 0.11.9
- cospend: 4.0.2
- dashboard: 7.14.0
- dav: 1.39.0
- eidlogin: 1.0.22
- event_update_notification: 2.9.0
- 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_external: 1.26.0
- files_fulltextsearch: 34.0.0
- files_lock: 34.0.1
- files_pdfviewer: 7.0.0-dev.0
- files_reminders: 1.7.0
- files_sharing: 1.26.0
- files_trashbin: 1.24.0
- files_versions: 1.27.0
- fileslibreofficeedit: 2.0.1
- firstrunwizard: 7.0.0-dev.0
- forms: 5.3.5
- fulltextsearch: 34.0.0
- fulltextsearch_elasticsearch: 34.0.0
- gestion: 3.2.5
- gpxpod: 8.3.0
- groupfolders: 22.0.6
- guests: 4.9.0
- impersonate: 5.0.0
- integration_mattermost: 3.2.0
- integration_openstreetmap: 4.2.0
- logreader: 7.0.0
- lookup_server_connector: 1.22.0
- mail: 5.10.11
- memories: 8.1.0
- music: 3.1.1
- nextcloud_announcements: 6.0.0
- notes: 6.0.1
- notifications: 7.0.0-dev.1
- oauth2: 1.22.0
- office: 1.0.0
- pantry: 0.24.0
- password_policy: 6.0.0-dev.0
- passwords: 2026.7.20
- phonetrack: 1.3.2
- photos: 7.0.0
- previewgenerator: 5.14.0
- privacy: 6.0.0-dev.1
- profile: 1.3.0
- provisioning_api: 1.24.0
- recognize: 12.0.0
- recommendations: 7.0.0
- registration: 3.0.0
- related_resources: 5.0.0-dev.0
- richdocuments: 11.1.0
- richdocumentscode: 26.4.104
- serverinfo: 6.0.0
- settings: 1.17.0
- sharebymail: 1.24.0
- side_menu: 6.0.1
- spreed: 24.0.3
- 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
- twofactor_backupcodes: 1.23.0
- twofactor_nextcloud_notification: 8.0.0
- 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
- whiteboard: 1.5.9
- workflowengine: 2.16.0
Disabled:
- context_chat: 5.4.0 (installed 5.4.0)
- deck: 1.17.4 (installed 1.17.4)
- encryption: 2.22.0 (installed 2.13.0)
- epubreader: 1.4.7 (installed 1.4.7)
- facerecognition: 0.9.70 (installed 0.9.70)
- files_antivirus: 6.3.2 (installed 6.3.2)
- files_bpm: 1.8.3 (installed 1.8.3)
- files_downloadlimit: 5.2.0 (installed 2.0.0)
- integration_github: 3.2.6 (installed 3.2.6)
- integration_gitlab: 5.0.0 (installed 5.0.0)
- integration_mastodon: 5.2.0 (installed 5.2.0)
- integration_onedrive: 3.5.2 (installed 3.5.2)
- integration_reddit: 2.3.0 (installed 2.3.0)
- maps: 1.7.1 (installed 1.7.1)
- notify_push: 1.3.5 (installed 1.3.5)
- oidc: 2.0.4 (installed 2.0.4)
- pto: 1.1.0 (installed 1.1.0)
- quota_warning: 1.24.0 (installed 1.24.0)
- radio: 1.0.3 (installed 1.0.3)
- sip_trip_phone: 1.2.0 (installed 1.2.0)
- stt_helper: 1.1.1 (installed 1.1.1)
- stt_whisper: 1.0.8 (installed 1.0.8)
- support: 6.0.0 (installed 1.12.0)
- suspicious_login: 12.0.0-dev.0 (installed 4.4.0)
- testing: 1.23.0
- translate: 2.2.0 (installed 2.2.0)
- twofactor_webauthn: 2.7.0 (installed 2.7.0)
- user_ldap: 1.25.0