[Bug]: PHP unlink error, no such file: `unlink(/var/www/nextcloud/data/appdata_[...]/richdocuments/remoteData/capabilities`

⚠️ 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

As discussed here: https://help.nextcloud.com/t/php-error-unlink-var-www-nextcloud-data-appdata-ocgfs89mpg4c-richdocuments-remotedata-capabilities-no-such-file-or-directory-at-var-www-nextcloud-lib-private-files-storage-local-php-348/198537

the system logs PHP errors like these:

[PHP] Error: unlink(/var/www/nextcloud/data/appdata_ocgfs89mpg4c/richdocuments/remoteData/capabilities): No such file or directory at /var/www/nextcloud/lib/private/Files/Storage/Local.php#348
	GET /ocs/v2.php/apps/notifications/api/v2/notifications?format=json

Steps to reproduce

Not clear. But all affected users seem to use Collabora Online - Built-in CODE Server

Expected behavior

No errors under the logging page.

Installation method

Community Manual installation with Archive

Nextcloud Server version

28

Operating system

Debian/Ubuntu

PHP engine version

PHP 8.1

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. 28 to 29)

Are you using the Nextcloud Server Encryption module?

None

What user-backends are you using?

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

Nextcloud Logs

{"reqId":"O736PgfFCb34EnaHt59Q","level":3,"time":"2024-08-13T16:50:10+00:00","remoteAddr":"redact","user":"user","app":"PHP","method":"GET","url":"/index.phps/api/v1/stats","message":"unlink(/mnt/nextcloud/data/appdata_ocyao8xfftvv/richdocuments/remoteData/discovery): No such file or directory at /var/www/nextcloud/lib/private/Files/Storage/Local.php#348","userAgent":"Mozilla/5.0 (X11; Linux x86_64; rv:127.0) Gecko/20100101 Firefox/127.0","version":"29.0.4.1","data":{"app":"PHP"},"id":"66bcace1b6880"}

Start at lib/private/Files/Storage/Local.php#348 and trace how richdocuments uses the remoteData/capabilities and remoteData/discovery paths with Collabora Online Built-in CODE. Review the linked forum discussion and the reported logs first. Done means identifying the cause and eliminating the erroneous missing-file errors, with a reproducible verification path.