[Bug]: Public share link fails with "Strict Cookie has not been found in request" and 412 Precondition Failed when clicking, but works when copy-pasting

[TomKamin1]

⚠️ 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

Hi,
I'm running a Nextcloud instance and encountering a strange behavior when using public share links.

When I click on a share link (e.g., from an email or messenger), I get an error:
{"error":"Strict Cookie has not been found in request"}

Additionally, the browser console shows a failed request:

GET https://cloud.mydomain.eu/public.php/dav/files/<file_id>/?accept=zip  
412 (Precondition Failed)

However, if I copy and paste the same URL manually into the browser's address bar, everything works fine — no errors.

It looks like the problem is a combination of:

• Cookies not being sent due to SameSite policies (Strict or Lax).
• WebDAV requests (like /public.php/dav/) failing when session/auth cookies are missing.

overwrite.cli.url and overwriteprotocol are properly set in config.php.

Steps to reproduce

1. Share a file/folder via public link.
2. Send the link via email or chat.
3. Click the link (don't paste manually).
4. Observe the cookie error and 412 precondition failure.

Expected behavior

Public shares should work reliably when clicked without requiring users to manually paste links.

Notes:

This appears to be a cookie/session handling issue, combined with WebDAV precondition checks.

Browser: [browser + version]

No major proxy misconfiguration detected.

Nextcloud Server version

31

Operating system

Debian/Ubuntu

PHP engine version

None

Web server

None

Database engine version

MariaDB

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

None

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

Configuration report

List of activated Apps

Nextcloud Signing status

Nextcloud Logs

Additional info

No response