[Bug]: EofException trying to subscribe to an ICS

⚠️ 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

I'm trying to add a calendar from a link. I can download the ICS and it validates. I can add it to other calendar apps (such as Thunderbird) without a problem. I can even subscribe in earlier versions of NC (Calendar 4.7.6 on NC 26.0.13 works fine). But on the latest versions, calendar 5.5.7 on NC 31.0.9 I see this in the logs: "EofException End of document reached prematurely" and the calendar items do not appear.

Steps to reproduce

1. In the calendar app, click the + button.
2. Select "New subscription from link (read-only)
3. Paste the URL and click the ->
4. New calendar appears in the Calendars list, but no items appear
5. Observe the EofException in the logs.

Expected behavior

Expect calendar would load and the items would appear.

Nextcloud Server version

31

Operating system

Debian/Ubuntu

PHP engine version

PHP 8.4

Web server

Apache (supported)

Database engine version

MySQL

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

None

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": {
        "apps_paths": [
            {
                "path": "\/snap\/nextcloud\/current\/htdocs\/apps",
                "url": "\/apps",
                "writable": false
            },
            {
                "path": "\/var\/snap\/nextcloud\/current\/nextcloud\/extra-apps",
                "url": "\/extra-apps",
                "writable": true
            }
        ],
        "supportedDatabases": [
            "mysql"
        ],
        "memcache.locking": "\\OC\\Memcache\\Redis",
        "memcache.local": "\\OC\\Memcache\\Redis",
        "redis": {
            "host": "***REMOVED SENSITIVE VALUE***",
            "port": 0
        },
        "log_type": "file",
        "logfile": "\/var\/snap\/nextcloud\/current\/logs\/nextcloud.log",
        "logfilemode": 416,
        "maintenance_window_start": 1,
        "instanceid": "***REMOVED SENSITIVE VALUE***",
        "passwordsalt": "***REMOVED SENSITIVE VALUE***",
        "secret": "***REMOVED SENSITIVE VALUE***",
        "trusted_domains": [
            "cloud.pardi.net"
        ],
        "datadirectory": "***REMOVED SENSITIVE VALUE***",
        "dbtype": "mysql",
        "version": "31.0.9.1",
        "overwrite.cli.url": "https:\/\/cloud.pardi.net",
        "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_smtpmode": "smtp",
        "mail_smtpsecure": "ssl",
        "mail_sendmailmode": "smtp",
        "mail_from_address": "***REMOVED SENSITIVE VALUE***",
        "mail_domain": "***REMOVED SENSITIVE VALUE***",
        "mail_smtphost": "***REMOVED SENSITIVE VALUE***",
        "mail_smtpport": "465",
        "mail_smtpauth": true,
        "mail_smtpname": "***REMOVED SENSITIVE VALUE***",
        "mail_smtppassword": "***REMOVED SENSITIVE VALUE***",
        "maintenance": false,
        "loglevel": 2,
        "theme": "",
        "app_install_overwrite": []
    }
}

List of activated Apps

Enabled:
  - activity: 4.0.0
  - app_api: 5.0.2
  - bruteforcesettings: 4.0.0
  - calendar: 5.5.7
  - circles: 31.0.0
  - cloud_federation_api: 1.14.0
  - comments: 1.21.0
  - contacts: 7.3.4
  - contactsinteraction: 1.12.0
  - dashboard: 7.11.0
  - dav: 1.33.0
  - documentserver_community: 0.2.0
  - federatedfilesharing: 1.21.0
  - federation: 1.21.0
  - files: 2.3.1
  - files_downloadlimit: 4.0.0
  - files_external: 1.23.0
  - files_pdfviewer: 4.0.0
  - files_reminders: 1.4.0
  - files_sharing: 1.23.1
  - files_trashbin: 1.21.0
  - files_versions: 1.24.0
  - firstrunwizard: 4.0.0
  - logreader: 4.0.0
  - lookup_server_connector: 1.19.0
  - mail: 5.5.11
  - nextcloud_announcements: 3.0.0
  - notes: 4.12.3
  - notifications: 4.0.0
  - oauth2: 1.19.1
  - onlyoffice: 9.11.0
  - password_policy: 3.0.0
  - photos: 4.0.0
  - privacy: 3.0.0
  - profile: 1.0.0
  - provisioning_api: 1.21.0
  - recommendations: 4.0.0
  - related_resources: 2.0.0
  - settings: 1.14.0
  - sharebymail: 1.21.0
  - smb_test: 0.3.12
  - spreed: 21.1.5
  - support: 3.0.0
  - survey_client: 3.0.0
  - systemtags: 1.21.1
  - tasks: 0.17.0
  - text: 5.0.0
  - theming: 2.6.1
  - twofactor_backupcodes: 1.20.0
  - user_status: 1.11.0
  - viewer: 4.0.0
  - weather_status: 1.11.0
  - webhook_listeners: 1.2.0
  - workflowengine: 2.13.0
Disabled:
  - admin_audit: 1.21.0
  - deck: 1.15.3 (installed 1.15.3)
  - encryption: 2.19.0
  - fileslibreofficeedit: 2.0.1 (installed 2.0.1)
  - integration_onedrive: 3.4.0 (installed 3.4.0)
  - officeonline: 3.1.0 (installed 3.1.0)
  - serverinfo: 3.0.0 (installed 3.0.0)
  - suspicious_login: 9.0.1
  - twofactor_nextcloud_notification: 5.0.0
  - twofactor_totp: 13.0.0-dev.0
  - user_ldap: 1.22.0

Nextcloud Signing status

No errors have been found.

Nextcloud Logs

{"reqId":"Qzm2Kh6DjHmg8uEgRgSj","level":2,"time":"2025-10-24T12:07:54+00:00","remoteAddr":"","user":"--","app":"dav","method":"","url":"--","message":"Subscription 47 could not be parsed","userAgent":"--","version":"31.0.9.1","exception":{"Exception":"Sabre\\VObject\\EofException","Message":"End of document reached prematurely","Code":0,"Trace":[{"file":"/snap/nextcloud/50464/htdocs/3rdparty/sabre/vobject/lib/Parser/MimeDir.php","line":150,"function":"readLine","class":"Sabre\\VObject\\Parser\\MimeDir","type":"->"},{"file":"/snap/nextcloud/50464/htdocs/3rdparty/sabre/vobject/lib/Parser/MimeDir.php","line":96,"function":"parseDocument","class":"Sabre\\VObject\\Parser\\MimeDir","type":"->"},{"file":"/snap/nextcloud/50464/htdocs/3rdparty/sabre/vobject/lib/Reader.php","line":47,"function":"parse","class":"Sabre\\VObject\\Parser\\MimeDir","type":"->"},{"file":"/snap/nextcloud/50464/htdocs/apps/dav/lib/CalDAV/WebcalCaching/Connection.php","line":108,"function":"read","class":"Sabre\\VObject\\Reader","type":"::"},{"file":"/snap/nextcloud/50464/htdocs/apps/dav/lib/CalDAV/WebcalCaching/RefreshWebcalService.php","line":61,"function":"queryWebcalFeed","class":"OCA\\DAV\\CalDAV\\WebcalCaching\\Connection","type":"->"},{"file":"/snap/nextcloud/50464/htdocs/apps/dav/lib/BackgroundJob/RefreshWebcalJob.php","line":73,"function":"refreshSubscription","class":"OCA\\DAV\\CalDAV\\WebcalCaching\\RefreshWebcalService","type":"->"},{"file":"/snap/nextcloud/50464/htdocs/lib/public/BackgroundJob/Job.php","line":61,"function":"run","class":"OCA\\DAV\\BackgroundJob\\RefreshWebcalJob","type":"->"},{"file":"/snap/nextcloud/50464/htdocs/apps/dav/lib/BackgroundJob/RefreshWebcalJob.php","line":66,"function":"start","class":"OCP\\BackgroundJob\\Job","type":"->"},{"file":"/snap/nextcloud/50464/htdocs/lib/public/BackgroundJob/Job.php","line":46,"function":"start","class":"OCA\\DAV\\BackgroundJob\\RefreshWebcalJob","type":"->"},{"file":"/snap/nextcloud/50464/htdocs/cron.php","line":170,"function":"execute","class":"OCP\\BackgroundJob\\Job","type":"->"}],"File":"/snap/nextcloud/50464/htdocs/3rdparty/sabre/vobject/lib/Parser/MimeDir.php","Line":294,"message":"Subscription 47 could not be parsed","exception":[],"CustomMessage":"Subscription 47 could not be parsed"},"id":"68fb6c2474497"}

Additional info

No response

Start at apps/dav/lib/CalDAV/WebcalCaching/Connection.php:108 and follow RefreshWebcalService.php and RefreshWebcalJob.php, using the reported subscription and its EofException as the reproduction. Compare the fetched ICS with the parsing path. Done means the subscription parses during refresh and its calendar items appear without the logged exception.