[Bug]: PHP Warning: Cannot modify header information - headers already sent in sabre/http Sapi.php during PROPFIND requests on .nomedia

### ⚠️ This issue respects the following points: ⚠️

- [x] This is a **bug**, not 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

Since enabling the notify_push (High Performance Backend) app and/or updating from 34.0.1 to 34.0.2   and optimizing client interactions, i observe intermittent PHP warnings in the Nextcloud log during WebDAV PROPFIND requests (specifically targeting .nomedia files, often routed through proxies/Cloudflare).

While synchronization and functionality are completely unaffected, these warnings clutter the logs.

[PHP] Warnung: Cannot modify header information - headers already sent by (output started at /var/www/nextcloud/3rdparty/sabre/http/lib/Message.php:117) at /var/www/nextcloud/3rdparty/sabre/http/lib/Sapi.php#68
	PROPFIND /public.php/webdav/blaaa/.nomemories
	von 172.xx.xxx.247 von -- um 26.07.2026, 21:50:53


### Steps to reproduce

1.Enable notify_push (High Performance Backend) with Redis and a proper reverse proxy chain.

2.Have clients (or sync tools) perform background WebDAV queries/PROPFIND requests (e.g., checking for .nomedia files).

3.Check the Nextcloud log.



### Expected behavior

WebDAV requests should complete without triggering PHP header warnings.

### Nextcloud Server version

34

### Operating system

Debian/Ubuntu

### PHP engine version

PHP 8.4

### Web server

Nginx

### Database engine version

MariaDB

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

after update from 34.0.1 to 34.0.2 

### Are you using the Nextcloud Server Encryption module?

Encryption is Disabled

### What user-backends are you using?

- [x] Default user-backend _(database)_
- [ ] LDAP/ Active Directory
- [ ] SSO - SAML
- [ ] Other

### Configuration report

```json
root@LXC-Nextcloud:~# occ config:list system
{
    "system": {
        "serverid": 1,
        "instanceid": "***REMOVED SENSITIVE VALUE***",
        "passwordsalt": "***REMOVED SENSITIVE VALUE***",
        "secret": "***REMOVED SENSITIVE VALUE***",
        "trusted_domains": [
            "10.0.10.12",
            "cloud2.underwater-way.com"
        ],
        "trusted_proxies": "***REMOVED SENSITIVE VALUE***",
        "datadirectory": "***REMOVED SENSITIVE VALUE***",
        "dbtype": "mysql",
        "version": "34.0.2.1",
        "overwrite.cli.url": "https:\/\/cloud2.underwater-way.com",
        "dbname": "***REMOVED SENSITIVE VALUE***",
        "dbhost": "***REMOVED SENSITIVE VALUE***",
        "dbtableprefix": "oc_",
        "mysql.utf8mb4": true,
        "dbuser": "***REMOVED SENSITIVE VALUE***",
        "dbpassword": "***REMOVED SENSITIVE VALUE***",
        "installed": true,
        "overwritehost": "cloud2.underwater-way.com",
        "activity_expire_days": 14,
        "allow_local_remote_servers": true,
        "auth.bruteforce.protection.enabled": true,
        "forbidden_filenames": [
            ".htaccess",
            "Thumbs.db",
            "thumbs.db"
        ],
        "cron_log": true,
        "default_phone_region": "DE",
        "enable_previews": true,
        "enabledPreviewProviders": [
            "OC\\Preview\\PNG",
            "OC\\Preview\\JPEG",
            "OC\\Preview\\GIF",
            "OC\\Preview\\BMP",
            "OC\\Preview\\XBitmap",
            "OC\\Preview\\Movie",
            "OC\\Preview\\PDF",
            "OC\\Preview\\MP3",
            "OC\\Preview\\TXT",
            "OC\\Preview\\MarkDown",
            "OC\\Preview\\HEIC",
            "OC\\Preview\\Movie",
            "OC\\Preview\\MKV",
            "OC\\Preview\\MP4",
            "OC\\Preview\\AVI"
        ],
        "filesystem_check_changes": 0,
        "filelocking.enabled": "true",
        "htaccess.RewriteBase": "\/",
        "integrity.check.disabled": false,
        "knowledgebaseenabled": false,
        "logfile": "\/var\/log\/nextcloud\/nextcloud.log",
        "debug": false,
        "loglevel": 3,
        "logtimezone": "Europe\/Berlin",
        "remember_login_cookie_lifetime": 7200,
        "session_lifetime": 7200,
        "session_keepalive": true,
        "auto_logout": true,
        "minimum.supported.desktop.version": "4.0.1",
        "memcache.local": "\\OC\\Memcache\\APCu",
        "memcache.locking": "\\OC\\Memcache\\Redis",
        "overwriteprotocol": "https",
        "preview_max_x": 1024,
        "preview_max_y": 768,
        "preview_max_scale_factor": 1,
        "profile.enabled": false,
        "redis": {
            "host": "***REMOVED SENSITIVE VALUE***",
            "port": 0,
            "password": "***REMOVED SENSITIVE VALUE***",
            "timeout": 0.5,
            "dbindex": 1
        },
        "quota_include_external_storage": false,
        "share_folder": "\/Freigaben",
        "skeletondirectory": "",
        "trashbin_retention_obligation": "auto, 7",
        "maintenance_window_start": 1,
        "maintenance": false,
        "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",
        "onlyoffice": {
            "jwt_secret": "***REMOVED SENSITIVE VALUE***",
            "jwt_header": "EUOFFICE"
        },
        "updater.secret": "***REMOVED SENSITIVE VALUE***",
        "theme": "",
        "versions_retention_obligation": "auto, 365",
        "simpleSignUpLink.shown": false,
        "upgrade.disable-web": false,
        "log.condition": {
            "apps": [
                "admin_audit"
            ]
        },
        "log_rotate_size": "0"
    }
}
```

### List of activated Apps

```shell
Enabled:
  - activity: 7.0.0
  - admin_audit: 1.24.0
  - appstore: 1.0.0
  - bruteforcesettings: 7.0.0
  - calendar: 6.5.1
  - circles: 34.0.0
  - cloud_federation_api: 1.18.0
  - comments: 1.24.0
  - contacts: 8.7.4
  - contactsinteraction: 1.15.0
  - dashboard: 7.14.0
  - dav: 1.39.0
  - eurooffice: 11.0.1
  - federatedfilesharing: 1.24.0
  - federation: 1.24.0
  - files: 2.6.0
  - files_downloadlimit: 5.2.0
  - 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
  - firstrunwizard: 7.0.0-dev.0
  - gpoddersync: 3.17.0
  - integration_paperless: 1.0.13
  - logreader: 7.0.0
  - lookup_server_connector: 1.22.0
  - memories: 8.1.0
  - nextcloud_announcements: 6.0.0
  - notes: 6.0.1
  - notifications: 7.0.0-dev.1
  - notify_push: 1.3.5
  - oauth2: 1.22.0
  - password_policy: 6.0.0-dev.0
  - photos: 7.0.0
  - 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
  - support: 6.0.0
  - survey_client: 6.0.0-dev.0
  - suspicious_login: 12.0.0-dev.0
  - text: 8.0.0
  - theming: 2.9.0
  - twofactor_backupcodes: 1.23.0
  - twofactor_totp: 16.0.0
  - updatenotification: 1.24.0
  - user_oidc: 8.10.1
  - user_status: 1.14.0
  - viewer: 7.0.0-dev.0
  - webhook_listeners: 1.6.0
  - workflowengine: 2.16.0
Disabled:
  - app_api: 34.0.0 (installed 32.0.0)
  - encryption: 2.22.0
  - files_external: 1.26.0
  - office: 1.0.0 (installed 1.0.0)
  - systemtags: 1.24.0 (installed 1.18.0)
  - twofactor_nextcloud_notification: 8.0.0
  - user_ldap: 1.25.0
  - weather_status: 1.14.0 (installed 1.10.0)
```

### Nextcloud Signing status

```shell
No errors have been found.
```

### Nextcloud Logs

```json
{"reqId":"nlGjfl72tqHq0f4bwvQ1","level":2,"time":"2026-07-26T21:50:52+02:00","remoteAddr":"172.71.141.247","user":"--","app":"PHP","method":"PROPFIND","url":"/public.php/webdav/%40Tauchen/2025/Michi%20Haushofer/2025.12.06/.nomemories","scriptName":"/public.php","message":"Cannot modify header information - headers already sent by (output started at /var/www/nextcloud/3rdparty/sabre/http/lib/Message.php:117) at /var/www/nextcloud/3rdparty/sabre/http/lib/Sapi.php#68","userAgent":"sabre-dav/4.6.0 (http://sabre.io/)","version":"34.0.2.1","data":{"app":"PHP"}}
{"reqId":"XV0eNYmAsVSdXXClYhPw","level":2,"time":"2026-07-26T21:50:52+02:00","remoteAddr":"172.71.141.247","user":"--","app":"PHP","method":"PROPFIND","url":"/public.php/webdav/%40Tauchen/2025/Michi%20Haushofer/2025.12.07/.nomedia","scriptName":"/public.php","message":"Cannot modify header information - headers already sent by (output started at /var/www/nextcloud/3rdparty/sabre/http/lib/Message.php:117) at /var/www/nextcloud/3rdparty/sabre/http/lib/Sapi.php#64","userAgent":"sabre-dav/4.6.0 (http://sabre.io/)","version":"34.0.2.1","data":{"app":"PHP"}}
{"reqId":"XV0eNYmAsVSdXXClYhPw","level":2,"time":"2026-07-26T21:50:52+02:00","remoteAddr":"172.71.141.247","user":"--","app":"PHP","method":"PROPFIND","url":"/public.php/webdav/%40Tauchen/2025/Michi%20Haushofer/2025.12.07/.nomedia","scriptName":"/public.php","message":"Cannot modify header information - headers already sent by (output started at /var/www/nextcloud/3rdparty/sabre/http/lib/Message.php:117) at /var/www/nextcloud/3rdparty/sabre/http/lib/Sapi.php#68","userAgent":"sabre-dav/4.6.0 (http://sabre.io/)","version":"34.0.2.1","data":{"app":"PHP"}}
{"reqId":"XV0eNYmAsVSdXXClYhPw","level":2,"time":"2026-07-26T21:50:52+02:00","remoteAddr":"172.71.141.247","user":"--","app":"PHP","method":"PROPFIND","url":"/public.php/webdav/%40Tauchen/2025/Michi%20Haushofer/2025.12.07/.nomedia","scriptName":"/public.php","message":"Cannot modify header information - headers already sent by (output started at /var/www/nextcloud/3rdparty/sabre/http/lib/Message.php:117) at /var/www/nextcloud/3rdparty/sabre/http/lib/Sapi.php#68","userAgent":"sabre-dav/4.6.0 (http://sabre.io/)","version":"34.0.2.1","data":{"app":"PHP"}}
{"reqId":"XV0eNYmAsVSdXXClYhPw","level":2,"time":"2026-07-26T21:50:52+02:00","remoteAddr":"172.71.141.247","user":"--","app":"PHP","method":"PROPFIND","url":"/public.php/webdav/%40Tauchen/2025/Michi%20Haushofer/2025.12.07/.nomedia","scriptName":"/public.php","message":"Cannot modify header information - headers already sent by (output started at /var/www/nextcloud/3rdparty/sabre/http/lib/Message.php:117) at /var/www/nextcloud/3rdparty/sabre/http/lib/Sapi.php#68","userAgent":"sabre-dav/4.6.0 (http://sabre.io/)","version":"34.0.2.1","data":{"app":"PHP"}}
{"reqId":"XV0eNYmAsVSdXXClYhPw","level":2,"time":"2026-07-26T21:50:52+02:00","remoteAddr":"172.71.141.247","user":"--","app":"PHP","method":"PROPFIND","url":"/public.php/webdav/%40Tauchen/2025/Michi%20Haushofer/2025.12.07/.nomedia","scriptName":"/public.php","message":"Cannot modify header information - headers already sent by (output started at /var/www/nextcloud/3rdparty/sabre/http/lib/Message.php:117) at /var/www/nextcloud/3rdparty/sabre/http/lib/Sapi.php#68","userAgent":"sabre-dav/4.6.0 (http://sabre.io/)","version":"34.0.2.1","data":{"app":"PHP"}}
{"reqId":"WZgNfbKZkmXreBSG04jl","level":2,"time":"2026-07-26T21:50:52+02:00","remoteAddr":"172.71.141.247","user":"--","app":"PHP","method":"PROPFIND","url":"/public.php/webdav/%40Tauchen/2025/Michi%20Haushofer/2025.12.07/.nomemories","scriptName":"/public.php","message":"Cannot modify header information - headers already sent by (output started at /var/www/nextcloud/3rdparty/sabre/http/lib/Message.php:117) at /var/www/nextcloud/3rdparty/sabre/http/lib/Sapi.php#64","userAgent":"sabre-dav/4.6.0 (http://sabre.io/)","version":"34.0.2.1","data":{"app":"PHP"}}
{"reqId":"WZgNfbKZkmXreBSG04jl","level":2,"time":"2026-07-26T21:50:52+02:00","remoteAddr":"172.71.141.247","user":"--","app":"PHP","method":"PROPFIND","url":"/public.php/webdav/%40Tauchen/2025/Michi%20Haushofer/2025.12.07/.nomemories","scriptName":"/public.php","message":"Cannot modify header information - headers already sent by (output started at /var/www/nextcloud/3rdparty/sabre/http/lib/Message.php:117) at /var/www/nextcloud/3rdparty/sabre/http/lib/Sapi.php#68","userAgent":"sabre-dav/4.6.0 (http://sabre.io/)","version":"34.0.2.1","data":{"app":"PHP"}}
{"reqId":"WZgNfbKZkmXreBSG04jl","level":2,"time":"2026-07-26T21:50:52+02:00","remoteAddr":"172.71.141.247","user":"--","app":"PHP","method":"PROPFIND","url":"/public.php/webdav/%40Tauchen/2025/Michi%20Haushofer/2025.12.07/.nomemories","scriptName":"/public.php","message":"Cannot modify header information - headers already sent by (output started at /var/www/nextcloud/3rdparty/sabre/http/lib/Message.php:117) at /var/www/nextcloud/3rdparty/sabre/http/lib/Sapi.php#68","userAgent":"sabre-dav/4.6.0 (http://sabre.io/)","version":"34.0.2.1","data":{"app":"PHP"}}
{"reqId":"WZgNfbKZkmXreBSG04jl","level":2,"time":"2026-07-26T21:50:52+02:00","remoteAddr":"172.71.141.247","user":"--","app":"PHP","method":"PROPFIND","url":"/public.php/webdav/%40Tauchen/2025/Michi%20Haushofer/2025.12.07/.nomemories","scriptName":"/public.php","message":"Cannot modify header information - headers already sent by (output started at /var/www/nextcloud/3rdparty/sabre/http/lib/Message.php:117) at /var/www/nextcloud/3rdparty/sabre/http/lib/Sapi.php#68","userAgent":"sabre-dav/4.6.0 (http://sabre.io/)","version":"34.0.2.1","data":{"app":"PHP"}}
{"reqId":"WZgNfbKZkmXreBSG04jl","level":2,"time":"2026-07-26T21:50:52+02:00","remoteAddr":"172.71.141.247","user":"--","app":"PHP","method":"PROPFIND","url":"/public.php/webdav/%40Tauchen/2025/Michi%20Haushofer/2025.12.07/.nomemories","scriptName":"/public.php","message":"Cannot modify header information - headers already sent by (output started at /var/www/nextcloud/3rdparty/sabre/http/lib/Message.php:117) at /var/www/nextcloud/3rdparty/sabre/http/lib/Sapi.php#68","userAgent":"sabre-dav/4.6.0 (http://sabre.io/)","version":"34.0.2.1","data":{"app":"PHP"}}
{"reqId":"jkN5w8KLi0R5vNW1SkFJ","level":2,"time":"2026-07-26T21:50:52+02:00","remoteAddr":"172.71.141.247","user":"--","app":"PHP","method":"PROPFIND","url":"/public.php/webdav/%40Tauchen/2025/Michi%20Haushofer/2025.12.08/.nomedia","scriptName":"/public.php","message":"Cannot modify header information - headers already sent by (output started at /var/www/nextcloud/3rdparty/sabre/http/lib/Message.php:117) at /var/www/nextcloud/3rdparty/sabre/http/lib/Sapi.php#64","userAgent":"sabre-dav/4.6.0 (http://sabre.io/)","version":"34.0.2.1","data":{"app":"PHP"}}
{"reqId":"jkN5w8KLi0R5vNW1SkFJ","level":2,"time":"2026-07-26T21:50:52+02:00","remoteAddr":"172.71.141.247","user":"--","app":"PHP","method":"PROPFIND","url":"/public.php/webdav/%40Tauchen/2025/Michi%20Haushofer/2025.12.08/.nomedia","scriptName":"/public.php","message":"Cannot modify header information - headers already sent by (output started at /var/www/nextcloud/3rdparty/sabre/http/lib/Message.php:117) at /var/www/nextcloud/3rdparty/sabre/http/lib/Sapi.php#68","userAgent":"sabre-dav/4.6.0 (http://sabre.io/)","version":"34.0.2.1","data":{"app":"PHP"}}
{"reqId":"jkN5w8KLi0R5vNW1SkFJ","level":2,"time":"2026-07-26T21:50:52+02:00","remoteAddr":"172.71.141.247","user":"--","app":"PHP","method":"PROPFIND","url":"/public.php/webdav/%40Tauchen/2025/Michi%20Haushofer/2025.12.08/.nomedia","scriptName":"/public.php","message":"Cannot modify header information - headers already sent by (output started at /var/www/nextcloud/3rdparty/sabre/http/lib/Message.php:117) at /var/www/nextcloud/3rdparty/sabre/http/lib/Sapi.php#68","userAgent":"sabre-dav/4.6.0 (http://sabre.io/)","version":"34.0.2.1","data":{"app":"PHP"}}
{"reqId":"jkN5w8KLi0R5vNW1SkFJ","level":2,"time":"2026-07-26T21:50:52+02:00","remoteAddr":"172.71.141.247","user":"--","app":"PHP","method":"PROPFIND","url":"/public.php/webdav/%40Tauchen/2025/Michi%20Haushofer/2025.12.08/.nomedia","scriptName":"/public.php","message":"Cannot modify header information - headers already sent by (output started at /var/www/nextcloud/3rdparty/sabre/http/lib/Message.php:117) at /var/www/nextcloud/3rdparty/sabre/http/lib/Sapi.php#68","userAgent":"sabre-dav/4.6.0 (http://sabre.io/)","version":"34.0.2.1","data":{"app":"PHP"}}
{"reqId":"jkN5w8KLi0R5vNW1SkFJ","level":2,"time":"2026-07-26T21:50:52+02:00","remoteAddr":"172.71.141.247","user":"--","app":"PHP","method":"PROPFIND","url":"/public.php/webdav/%40Tauchen/2025/Michi%20Haushofer/2025.12.08/.nomedia","scriptName":"/public.php","message":"Cannot modify header information - headers already sent by (output started at /var/www/nextcloud/3rdparty/sabre/http/lib/Message.php:117) at /var/www/nextcloud/3rdparty/sabre/http/lib/Sapi.php#68","userAgent":"sabre-dav/4.6.0 (http://sabre.io/)","version":"34.0.2.1","data":{"app":"PHP"}}
{"reqId":"gByq8hfLji4Z2cI0ff5O","level":2,"time":"2026-07-26T21:50:53+02:00","remoteAddr":"172.71.141.247","user":"--","app":"PHP","method":"PROPFIND","url":"/public.php/webdav/%40Tauchen/2025/Michi%20Haushofer/2025.12.08/.nomemories","scriptName":"/public.php","message":"Cannot modify header information - headers already sent by (output started at /var/www/nextcloud/3rdparty/sabre/http/lib/Message.php:117) at /var/www/nextcloud/3rdparty/sabre/http/lib/Sapi.php#64","userAgent":"sabre-dav/4.6.0 (http://sabre.io/)","version":"34.0.2.1","data":{"app":"PHP"}}
{"reqId":"gByq8hfLji4Z2cI0ff5O","level":2,"time":"2026-07-26T21:50:53+02:00","remoteAddr":"172.71.141.247","user":"--","app":"PHP","method":"PROPFIND","url":"/public.php/webdav/%40Tauchen/2025/Michi%20Haushofer/2025.12.08/.nomemories","scriptName":"/public.php","message":"Cannot modify header information - headers already sent by (output started at /var/www/nextcloud/3rdparty/sabre/http/lib/Message.php:117) at /var/www/nextcloud/3rdparty/sabre/http/lib/Sapi.php#68","userAgent":"sabre-dav/4.6.0 (http://sabre.io/)","version":"34.0.2.1","data":{"app":"PHP"}}
{"reqId":"gByq8hfLji4Z2cI0ff5O","level":2,"time":"2026-07-26T21:50:53+02:00","remoteAddr":"172.71.141.247","user":"--","app":"PHP","method":"PROPFIND","url":"/public.php/webdav/%40Tauchen/2025/Michi%20Haushofer/2025.12.08/.nomemories","scriptName":"/public.php","message":"Cannot modify header information - headers already sent by (output started at /var/www/nextcloud/3rdparty/sabre/http/lib/Message.php:117) at /var/www/nextcloud/3rdparty/sabre/http/lib/Sapi.php#68","userAgent":"sabre-dav/4.6.0 (http://sabre.io/)","version":"34.0.2.1","data":{"app":"PHP"}}
{"reqId":"gByq8hfLji4Z2cI0ff5O","level":2,"time":"2026-07-26T21:50:53+02:00","remoteAddr":"172.71.141.247","user":"--","app":"PHP","method":"PROPFIND","url":"/public.php/webdav/%40Tauchen/2025/Michi%20Haushofer/2025.12.08/.nomemories","scriptName":"/public.php","message":"Cannot modify header information - headers already sent by (output started at /var/www/nextcloud/3rdparty/sabre/http/lib/Message.php:117) at /var/www/nextcloud/3rdparty/sabre/http/lib/Sapi.php#68","userAgent":"sabre-dav/4.6.0 (http://sabre.io/)","version":"34.0.2.1","data":{"app":"PHP"}}
{"reqId":"gByq8hfLji4Z2cI0ff5O","level":2,"time":"2026-07-26T21:50:53+02:00","remoteAddr":"172.71.141.247","user":"--","app":"PHP","method":"PROPFIND","url":"/public.php/webdav/%40Tauchen/2025/Michi%20Haushofer/2025.12.08/.nomemories","scriptName":"/public.php","message":"Cannot modify header information - headers already sent by (output started at /var/www/nextcloud/3rdparty/sabre/http/lib/Message.php:117) at /var/www/nextcloud/3rdparty/sabre/http/lib/Sapi.php#68","userAgent":"sabre-dav/4.6.0 (http://sabre.io/)","version":"34.0.2.1","data":{"app":"PHP"}}
{"reqId":"llygTC8Fqghb3Yg2XOtE","level":2,"time":"2026-07-26T21:50:53+02:00","remoteAddr":"172.71.141.247","user":"--","app":"PHP","method":"PROPFIND","url":"/public.php/webdav/%40Tauchen/2025/Peter2025/.nomedia","scriptName":"/public.php","message":"Cannot modify header information - headers already sent by (output started at /var/www/nextcloud/3rdparty/sabre/http/lib/Message.php:117) at /var/www/nextcloud/3rdparty/sabre/http/lib/Sapi.php#64","userAgent":"sabre-dav/4.6.0 (http://sabre.io/)","version":"34.0.2.1","data":{"app":"PHP"}}
{"reqId":"llygTC8Fqghb3Yg2XOtE","level":2,"time":"2026-07-26T21:50:53+02:00","remoteAddr":"172.71.141.247","user":"--","app":"PHP","method":"PROPFIND","url":"/public.php/webdav/%40Tauchen/2025/Peter2025/.nomedia","scriptName":"/public.php","message":"Cannot modify header information - headers already sent by (output started at /var/www/nextcloud/3rdparty/sabre/http/lib/Message.php:117) at /var/www/nextcloud/3rdparty/sabre/http/lib/Sapi.php#68","userAgent":"sabre-dav/4.6.0 (http://sabre.io/)","version":"34.0.2.1","data":{"app":"PHP"}}
{"reqId":"llygTC8Fqghb3Yg2XOtE","level":2,"time":"2026-07-26T21:50:53+02:00","remoteAddr":"172.71.141.247","user":"--","app":"PHP","method":"PROPFIND","url":"/public.php/webdav/%40Tauchen/2025/Peter2025/.nomedia","scriptName":"/public.php","message":"Cannot modify header information - headers already sent by (output started at /var/www/nextcloud/3rdparty/sabre/http/lib/Message.php:117) at /var/www/nextcloud/3rdparty/sabre/http/lib/Sapi.php#68","userAgent":"sabre-dav/4.6.0 (http://sabre.io/)","version":"34.0.2.1","data":{"app":"PHP"}}
{"reqId":"llygTC8Fqghb3Yg2XOtE","level":2,"time":"2026-07-26T21:50:53+02:00","remoteAddr":"172.71.141.247","user":"--","app":"PHP","method":"PROPFIND","url":"/public.php/webdav/%40Tauchen/2025/Peter2025/.nomedia","scriptName":"/public.php","message":"Cannot modify header information - headers already sent by (output started at /var/www/nextcloud/3rdparty/sabre/http/lib/Message.php:117) at /var/www/nextcloud/3rdparty/sabre/http/lib/Sapi.php#68","userAgent":"sabre-dav/4.6.0 (http://sabre.io/)","version":"34.0.2.1","data":{"app":"PHP"}}
{"reqId":"llygTC8Fqghb3Yg2XOtE","level":2,"time":"2026-07-26T21:50:53+02:00","remoteAddr":"172.71.141.247","user":"--","app":"PHP","method":"PROPFIND","url":"/public.php/webdav/%40Tauchen/2025/Peter2025/.nomedia","scriptName":"/public.php","message":"Cannot modify header information - headers already sent by (output started at /var/www/nextcloud/3rdparty/sabre/http/lib/Message.php:117) at /var/www/nextcloud/3rdparty/sabre/http/lib/Sapi.php#68","userAgent":"sabre-dav/4.6.0 (http://sabre.io/)","version":"34.0.2.1","data":{"app":"PHP"}}
{"reqId":"AJJqLSWjU5w5IWSgvsSO","level":2,"time":"2026-07-26T21:50:53+02:00","remoteAddr":"172.71.141.247","user":"--","app":"PHP","method":"PROPFIND","url":"/public.php/webdav/%40Tauchen/2025/Peter2025/.nomemories","scriptName":"/public.php","message":"Cannot modify header information - headers already sent by (output started at /var/www/nextcloud/3rdparty/sabre/http/lib/Message.php:117) at /var/www/nextcloud/3rdparty/sabre/http/lib/Sapi.php#64","userAgent":"sabre-dav/4.6.0 (http://sabre.io/)","version":"34.0.2.1","data":{"app":"PHP"}}
{"reqId":"AJJqLSWjU5w5IWSgvsSO","level":2,"time":"2026-07-26T21:50:53+02:00","remoteAddr":"172.71.141.247","user":"--","app":"PHP","method":"PROPFIND","url":"/public.php/webdav/%40Tauchen/2025/Peter2025/.nomemories","scriptName":"/public.php","message":"Cannot modify header information - headers already sent by (output started at /var/www/nextcloud/3rdparty/sabre/http/lib/Message.php:117) at /var/www/nextcloud/3rdparty/sabre/http/lib/Sapi.php#68","userAgent":"sabre-dav/4.6.0 (http://sabre.io/)","version":"34.0.2.1","data":{"app":"PHP"}}
{"reqId":"AJJqLSWjU5w5IWSgvsSO","level":2,"time":"2026-07-26T21:50:53+02:00","remoteAddr":"172.71.141.247","user":"--","app":"PHP","method":"PROPFIND","url":"/public.php/webdav/%40Tauchen/2025/Peter2025/.nomemories","scriptName":"/public.php","message":"Cannot modify header information - headers already sent by (output started at /var/www/nextcloud/3rdparty/sabre/http/lib/Message.php:117) at /var/www/nextcloud/3rdparty/sabre/http/lib/Sapi.php#68","userAgent":"sabre-dav/4.6.0 (http://sabre.io/)","version":"34.0.2.1","data":{"app":"PHP"}}
{"reqId":"AJJqLSWjU5w5IWSgvsSO","level":2,"time":"2026-07-26T21:50:53+02:00","remoteAddr":"172.71.141.247","user":"--","app":"PHP","method":"PROPFIND","url":"/public.php/webdav/%40Tauchen/2025/Peter2025/.nomemories","scriptName":"/public.php","message":"Cannot modify header information - headers already sent by (output started at /var/www/nextcloud/3rdparty/sabre/http/lib/Message.php:117) at /var/www/nextcloud/3rdparty/sabre/http/lib/Sapi.php#68","userAgent":"sabre-dav/4.6.0 (http://sabre.io/)","version":"34.0.2.1","data":{"app":"PHP"}}
{"reqId":"AJJqLSWjU5w5IWSgvsSO","level":2,"time":"2026-07-26T21:50:53+02:00","remoteAddr":"172.71.141.247","user":"--","app":"PHP","method":"PROPFIND","url":"/public.php/webdav/%40Tauchen/2025/Peter2025/.nomemories","scriptName":"/public.php","message":"Cannot modify header information - headers already sent by (output started at /var/www/nextcloud/3rdparty/sabre/http/lib/Message.php:117) at /var/www/nextcloud/3rdparty/sabre/http/lib/Sapi.php#68","userAgent":"sabre-dav/4.6.0 (http://sabre.io/)","version":"34.0.2.1","data":{"app":"PHP"}}
```

### Additional info

- i made a update from/to 34.0.1/34.0.2 

- i installed and configured notify_push

- and made following changes in the config:

```
occ config:system:set remember_login_cookie_lifetime --value="1800"
occ config:system:set log_rotate_size --value="104857600"
occ config:system:set trashbin_retention_obligation --value="auto, 7"
occ config:system:set versions_retention_obligation --value="auto, 365"
occ config:system:set simpleSignUpLink.shown --type=bool --value=false
occ config:system:set upgrade.disable-web --type=bool --value=true
occ config:app:set text workspace_available --value=0
occ config:system:set loglevel --value="2"
occ config:app:set settings profile_enabled_by_default --value="0"
occ app:enable admin_audit
occ config:app:set admin_audit logfile --value="/var/log/nextcloud/audit.log"
occ config:system:set log.condition apps 0 --value admin_audit
```

- and
```
`'remember_login_cookie_lifetime' => 7200,
'session_lifetime' => 7200,
'session_keepalive' => true,
'auto_logout' => true,`
```
- and in /etc/php/8.4/fpm/php.ini
```session.gc_maxlifetime = 7200```


- and in /etc/sysctl.d/100-nextcloud.conf
```
# Schutz gegen IP-Spoofing (IPv4 und IPv6)
net.ipv4.conf.all.rp_filter = 1
net.ipv4.conf.default.rp_filter = 1
net.ipv6.conf.all.accept_source_route = 0
net.ipv6.conf.default.accept_source_route = 0

# Schutz gegen TCP-SYN-Flooding (IPv4)
net.ipv4.tcp_syncookies = 1
net.ipv4.tcp_max_syn_backlog = 4096
net.ipv4.tcp_synack_retries = 2
net.core.somaxconn = 1024

# ICMP Echo Ignore Broadcasts (IPv4)
net.ipv4.icmp_echo_ignore_broadcasts = 1

# ICMP Redirects deaktivieren (IPv4 und IPv6)
net.ipv4.conf.all.accept_redirects = 0
net.ipv6.conf.all.accept_redirects = 0
net.ipv4.conf.default.accept_redirects = 0
net.ipv6.conf.default.accept_redirects = 0

# Sourcen-Routing deaktivieren (IPv4 und IPv6)
net.ipv4.conf.all.accept_source_route = 0
net.ipv6.conf.all.accept_source_route = 0
net.ipv4.conf.default.accept_source_route = 0
net.ipv6.conf.default.accept_source_route = 0

# TCP-Timestamps deaktivieren (IPv4)
net.ipv4.tcp_timestamps = 0

# Loggen von Martian-Paketen (IPv4 und IPv6)
net.ipv4.conf.all.log_martians = 1
net.ipv4.conf.default.log_martians = 1
net.ipv6.conf.all.log_martians = 1
net.ipv6.conf.default.log_martians = 1

# Maximale Anzahl von halb offenen Verbindungen (IPv4)
net.ipv4.tcp_max_syn_backlog = 4096

# Netzwerkspeichergrößen erhöhen (IPv4 und IPv6)
net.core.rmem_max = 16777216
net.core.wmem_max = 16777216
net.core.rmem_default = 262144
net.core.wmem_default = 262144
net.core.optmem_max = 40960

# Maximale Anzahl von Verbindungstrackings erhöhen (IPv4 und IPv6)
net.netfilter.nf_conntrack_max = 262144
net.netfilter.nf_conntrack_tcp_timeout_established = 1800

# Maximaler Backlog für Netzwerkgeräte erhöhen (IPv4 und IPv6)
net.core.netdev_max_backlog = 5000

# TCP-Verbindungseinstellungen optimieren (IPv4)
net.ipv4.tcp_fin_timeout = 15
net.ipv4.tcp_keepalive_time = 300
net.ipv4.tcp_keepalive_probes = 5
net.ipv4.tcp_keepalive_intvl = 15

# Datei-Deskriptor-Limits erhöhen
fs.file-max = 2097152

# TCP-Warteschlangen (Read/Write Queues) erhöhen (IPv4)
net.ipv4.tcp_rmem = 4096 87380 16777216
net.ipv4.tcp_wmem = 4096 65536 16777216

# TCP-Window-Scaling aktivieren (IPv4)
net.ipv4.tcp_window_scaling = 1

# TCP-Memory-Management optimieren (IPv4)
net.ipv4.tcp_mem = 50576 64768 98152

# Reverse Path Filtering aktivieren (IPv4 und IPv6)
net.ipv4.conf.all.rp_filter = 1
net.ipv4.conf.default.rp_filter = 1
net.ipv6.conf.all.rp_filter = 1
net.ipv6.conf.default.rp_filter = 1

# TCP Fast Open aktivieren (optional, IPv4)
net.ipv4.tcp_fastopen = 3

# ARP-Caching verbessern (IPv4)
net.ipv4.neigh.default.gc_thresh1 = 1024
net.ipv4.neigh.default.gc_thresh2 = 2048
net.ipv4.neigh.default.gc_thresh3 = 4096
```

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[Bug]: PHP Warning: Cannot modify header information - headers already sent in sabre/http Sapi.php during PROPFIND requests on .nomedia #62545

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[Bug]: PHP Warning: Cannot modify header information - headers already sent in sabre/http Sapi.php during PROPFIND requests on .nomedia #62545

Description

⚠️ This issue respects the following points: ⚠️

Bug description

Steps to reproduce

Expected behavior

Nextcloud Server version

Operating system

PHP engine version

Web server

Database engine version

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

Are you using the Nextcloud Server Encryption module?

What user-backends are you using?

Configuration report

List of activated Apps

Nextcloud Signing status

Nextcloud Logs

Additional info

Metadata

Metadata

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