[Bug]: "Failed to create Templates directory" error when logging in for the first time with a Guest account

⚠️ 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

The issue seems to be when the user has a space quota of 0, the templates can not be copied.

{
    "reqId": "Kr0yPTfQWPKASDCVem5J",
    "level": 3,
    "time": "2025-07-07T16:02:50+02:00",
    "remoteAddr": "x.x.x.x",
    "user": "guest_email@domain.com",
    "app": "files_templates",
    "method": "POST",
    "url": "/login",
    "message": "Failed to initialize templates directory to user language en for guest_email@domain.com",
    "userAgent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/136.0.0.0 Safari/537.36 Edg/136.0.0.0",
    "version": "31.0.6.3",
    "exception": {
        "Exception": "OCP\\Files\\NotPermittedException",
        "Message": "Could not create folder \"/guest_email@domain.com/files/./Templates\"",
        "Code": 0,
        "Trace": [
            {
                "file": "/data/nextcloud/lib/private/Files/Template/TemplateManager.php",
                "line": 367,
                "function": "newFolder",
                "class": "OC\\Files\\Node\\Folder",
                "type": "->"
            },
            {
                "file": "/data/nextcloud/lib/private/legacy/OC_Util.php",
                "line": 166,
                "function": "initializeTemplateDirectory",
                "class": "OC\\Files\\Template\\TemplateManager",
                "type": "->"
            },
            {
                "file": "/data/nextcloud/lib/private/User/Session.php",
                "line": 521,
                "function": "copySkeleton",
                "class": "OC_Util",
                "type": "::"
            },
            {
                "file": "/data/nextcloud/lib/private/User/Session.php",
                "line": 357,
                "function": "prepareUserLogin",
                "class": "OC\\User\\Session",
                "type": "->"
            },
            {
                "file": "/data/nextcloud/lib/private/Authentication/Login/CompleteLoginCommand.php",
                "line": 22,
                "function": "completeLogin",
                "class": "OC\\User\\Session",
                "type": "->",
                "args": [
                    "*** sensitive parameters replaced ***"
                ]
            },
            {
                "file": "/data/nextcloud/lib/private/Authentication/Login/ALoginCommand.php",
                "line": 22,
                "function": "process",
                "class": "OC\\Authentication\\Login\\CompleteLoginCommand",
                "type": "->"
            },
            {
                "file": "/data/nextcloud/lib/private/Authentication/Login/LoggedInCheckCommand.php",
                "line": 41,
                "function": "processNextOrFinishSuccessfully",
                "class": "OC\\Authentication\\Login\\ALoginCommand",
                "type": "->"
            },
            {
                "file": "/data/nextcloud/lib/private/Authentication/Login/ALoginCommand.php",
                "line": 22,
                "function": "process",
                "class": "OC\\Authentication\\Login\\LoggedInCheckCommand",
                "type": "->"
            },
            {
                "file": "/data/nextcloud/lib/private/Authentication/Login/EmailLoginCommand.php",
                "line": 51,
                "function": "processNextOrFinishSuccessfully",
                "class": "OC\\Authentication\\Login\\ALoginCommand",
                "type": "->"
            },
            {
                "file": "/data/nextcloud/lib/private/Authentication/Login/ALoginCommand.php",
                "line": 22,
                "function": "process",
                "class": "OC\\Authentication\\Login\\EmailLoginCommand",
                "type": "->"
            },
            {
                "file": "/data/nextcloud/lib/private/Authentication/Login/UidLoginCommand.php",
                "line": 36,
                "function": "processNextOrFinishSuccessfully",
                "class": "OC\\Authentication\\Login\\ALoginCommand",
                "type": "->"
            },
            {
                "file": "/data/nextcloud/lib/private/Authentication/Login/ALoginCommand.php",
                "line": 22,
                "function": "process",
                "class": "OC\\Authentication\\Login\\UidLoginCommand",
                "type": "->"
            },
            {
                "file": "/data/nextcloud/lib/private/Authentication/Login/UserDisabledCheckCommand.php",
                "line": 39,
                "function": "processNextOrFinishSuccessfully",
                "class": "OC\\Authentication\\Login\\ALoginCommand",
                "type": "->"
            },
            {
                "file": "/data/nextcloud/lib/private/Authentication/Login/ALoginCommand.php",
                "line": 22,
                "function": "process",
                "class": "OC\\Authentication\\Login\\UserDisabledCheckCommand",
                "type": "->"
            },
            {
                "file": "/data/nextcloud/lib/private/Authentication/Login/PreLoginHookCommand.php",
                "line": 34,
                "function": "processNextOrFinishSuccessfully",
                "class": "OC\\Authentication\\Login\\ALoginCommand",
                "type": "->"
            },
            {
                "file": "/data/nextcloud/lib/private/Authentication/Login/Chain.php",
                "line": 45,
                "function": "process",
                "class": "OC\\Authentication\\Login\\PreLoginHookCommand",
                "type": "->"
            },
            {
                "file": "/data/nextcloud/core/Controller/LoginController.php",
                "line": 344,
                "function": "process",
                "class": "OC\\Authentication\\Login\\Chain",
                "type": "->"
            },
            {
                "file": "/data/nextcloud/lib/private/AppFramework/Http/Dispatcher.php",
                "line": 200,
                "function": "tryLogin",
                "class": "OC\\Core\\Controller\\LoginController",
                "type": "->",
                "args": [
                    "*** sensitive parameters replaced ***"
                ]
            },
            {
                "file": "/data/nextcloud/lib/private/AppFramework/Http/Dispatcher.php",
                "line": 114,
                "function": "executeController",
                "class": "OC\\AppFramework\\Http\\Dispatcher",
                "type": "->"
            },
            {
                "file": "/data/nextcloud/lib/private/AppFramework/App.php",
                "line": 161,
                "function": "dispatch",
                "class": "OC\\AppFramework\\Http\\Dispatcher",
                "type": "->"
            },
            {
                "file": "/data/nextcloud/lib/private/Route/Router.php",
                "line": 307,
                "function": "main",
                "class": "OC\\AppFramework\\App",
                "type": "::"
            },
            {
                "file": "/data/nextcloud/lib/base.php",
                "line": 1040,
                "function": "match",
                "class": "OC\\Route\\Router",
                "type": "->"
            },
            {
                "file": "/data/nextcloud/index.php",
                "line": 24,
                "function": "handleRequest",
                "class": "OC",
                "type": "::"
            }
        ],
        "File": "/data/nextcloud/lib/private/Files/Node/Folder.php",
        "Line": 132,
        "message": "Failed to initialize templates directory to user language en for guest_email@domain.com",
        "exception": {},
        "CustomMessage": "Failed to initialize templates directory to user language en for guest_email@domain.com"
    }
}

Steps to reproduce

1. Install guest app and at least one file editor (e.g. NC text)
2. Create guest access to a folder
3. Login as the guest
4. See error in log

Expected behavior

No errors

Nextcloud Server version

master

Operating system

Debian/Ubuntu

PHP engine version

PHP 8.2

Web server

Nginx

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

Start with lib/private/Files/Template/TemplateManager.php around line 367, then trace the login flow through lib/private/User/Session.php as shown in the stack trace. Reproduce a first login with a guest account whose quota is zero and verify that template initialization completes without an error in the log.