[Bug]: Nextcloud reports errors on requests from nextcloud-clients and carddav/caldav-clients when being in maintenance mode

⚠️ 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 (I've searched it).
  This is the according thread in the Nextcloud-Forum (only in german):
  https://help.nextcloud.com/t/servermaintenancemode-das-system-befindet-sich-im-wartungsmodus/233826
• 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

An Error is logged with caldav/carddav requests, if Nextcloud is in maintenance mode.

Steps to reproduce

1. php occ maintenance:mode --on
2. issue a caldav/carddav request
3. check Nextcloud log

Expected behavior

I think the loglevel ERROR for this happening is set to high. loglevel INFO would suffice.

Nextcloud Server version

32

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?

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

List of activated Apps

Nextcloud Signing status

No errors have been found.

Nextcloud Logs

{"reqId":"4yS869z198evyX4KhI1J","level":3,"time":"2025-10-21T11:58:31+02:00","remoteAddr":"1.2.3.4","user":"--","app":"no app in context","method":"REPORT","url":"/nextcloud/remote.php/dav/addressbooks/users/<USERNAME>/contacts/","message":"Uncaught exception","userAgent":"iOS/26.0.1 (23A355) dataaccessd/1.0","version":"32.0.0.13","exception":{"Exception":"OCA\\DAV\\Exception\\ServerMaintenanceMode","Message":"Das System befindet sich im Wartungsmodus.","Code":0,"Trace":[{"file":"/var/www/nextcloud/3rdparty/sabre/event/lib/WildcardEmitterTrait.php","line":89,"function":"checkMaintenanceMode","class":"OCA\\DAV\\Connector\\Sabre\\MaintenancePlugin","type":"->"},{"file":"/var/www/nextcloud/3rdparty/sabre/dav/lib/DAV/Server.php","line":456,"function":"emit","class":"Sabre\\DAV\\Server","type":"->"},{"file":"/var/www/nextcloud/apps/dav/lib/Connector/Sabre/Server.php","line":211,"function":"invokeMethod","class":"Sabre\\DAV\\Server","type":"->"},{"file":"/var/www/nextcloud/apps/dav/lib/Server.php","line":424,"function":"start","class":"OCA\\DAV\\Connector\\Sabre\\Server","type":"->"},{"file":"/var/www/nextcloud/apps/dav/appinfo/v2/remote.php","line":22,"function":"exec","class":"OCA\\DAV\\Server","type":"->"},{"file":"/var/www/nextcloud/remote.php","line":151,"args":["/var/www/nextcloud/apps/dav/appinfo/v2/remote.php"],"function":"require_once"}],"File":"/var/www/nextcloud/apps/dav/lib/Connector/Sabre/MaintenancePlugin.php","Line":65,"message":"Uncaught exception","exception":{},"CustomMessage":"Uncaught exception"}}

Additional info

If needed, I'll happily provide the output of the following two commands, but I think it is irrelevant for this bug.

php occ config:list system
php occ app:list

EDIT: a user posted this in the Nextcloud forum - I created this issue as I am also affected.
Link to Nextcloud-Forum: https://help.nextcloud.com/t/servermaintenancemode-das-system-befindet-sich-im-wartungsmodus/233826

Start with apps/dav/lib/Connector/Sabre/MaintenancePlugin.php at line 65, then reproduce the issue with php occ maintenance:mode --on and a CalDAV or CardDAV request. Confirm the maintenance-mode exception is logged at INFO rather than ERROR, and verify the resulting Nextcloud log.