[Bug]: Application without an icon is causing a runtime exception

⚠️ 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

A third-party application without a navigations/navigation/icon entry in the appinfo/info.xml file is causing a runtime exception once the app is enabled, because the default-app-icon.svg file cannot be found.

The issue seems to be that the default-app-icon.svg file is shipped in this folder:

core/img/places/default-app-icon.svg

The lib/private/NavigationManager.php tries to get the imagePath like this:

if ($icon === null) {
  $icon = $this->urlGenerator->imagePath('core', 'default-app-icon');
}

The imagePath function in the lib/private/URLGenerator.php file has a very large if/else block for searching all kinds of folders, but the core/img/places folder is not part of that.

Based on the developer manual the navigations/navigation/icon entry is optional, so Nextcloud should be able to handle it:

https://docs.nextcloud.com/server/latest/developer_manual/app_development/info.html

Steps to reproduce

1. Have a working Nextcloud installation, make sure the web interface works

2. Generate a helloworld application with the application generator:

   https://apps.nextcloud.com/developer/apps/generate

3. Extract the archive, put it into the apps folder, give it proper permissions, etc.

4. Edit the appinfo/info.xml file manually, remove the navigations/navigation/icon line entirely.

5. Enable the application with occ app:enable helloworld

6. Refresh the Nextcloud page in your browser, you should see a runtime exception with an error message

Expected behavior

Nextcloud should display the usual web interface instead of the runtime exception.

Nextcloud Server version

32

Operating system

Other

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?

Fresh Nextcloud Server install

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

{"reqId":"lpHmBHRz36uuCcFhxJ2V","level":3,"time":"2026-04-20T11:31:45+00:00","remoteAddr":"192.168.2.200","user":"udi","app":"index","method":"GET","url":"/index.phpboard/","scriptName":"/index.php","message":"image not found: image:default-app-icon webroot: serverroot:/var/www/nextcloud/htdocs","userAgent":"Mozilla/5.0 (X11; Linux x86_64; rv:149.0) Gecko/20100101 Firefox/149.0","version":"32.0.6.1","exception":{"Exception":"RuntimeException","Message":"image not found: image:default-app-icon webroot: serverroot:/var/www/nextcloud/htdocs","Code":0,"Trace":[{"file":"/var/www/nextcloud/htdocs/lib/private/NavigationManager.php","line":378,"function":"imagePath","class":"OC\\URLGenerator","type":"->","args":["core","default-app-icon"]},{"file":"/var/www/nextcloud/htdocs/lib/private/NavigationManager.php","line":125,"function":"init","class":"OC\\NavigationManager","type":"->","args":[]},{"file":"/var/www/nextcloud/htdocs/lib/private/TemplateLayout.php","line":77,"function":"getAll","class":"OC\\NavigationManager","type":"->","args":[]},{"file":"/var/www/nextcloud/htdocs/lib/private/Template/Template.php","line":115,"function":"getPageTemplate","class":"OC\\TemplateLayout","type":"->","args":["user","dashboard"]},{"file":"/var/www/nextcloud/htdocs/lib/public/AppFramework/Http/TemplateResponse.php","line":195,"function":"fetchPage","class":"OC\\Template\\Template","type":"->","args":[{"id-app-content":"#app-dashboard","id-app-navigation":null,"pageTitle":"Ir\u00e1ny\u00edt\u00f3pult"}]},{"file":"/var/www/nextcloud/htdocs/lib/private/AppFramework/Http/Dispatcher.php","line":163,"function":"render","class":"OCP\\AppFramework\\Http\\TemplateResponse","type":"->","args":[]},{"file":"/var/www/nextcloud/htdocs/lib/private/AppFramework/App.php","line":153,"function":"dispatch","class":"OC\\AppFramework\\Http\\Dispatcher","type":"->","args":[{"__class__":"OCA\\Dashboard\\Controller\\DashboardController"},"index"]},{"file":"/var/www/nextcloud/htdocs/lib/private/Route/Router.php","line":321,"function":"main","class":"OC\\AppFramework\\App","type":"::","args":["OCA\\Dashboard\\Controller\\DashboardController","index",{"__class__":"OC\\AppFramework\\DependencyInjection\\DIContainer"},{"_route":"dashboard.dashboard.index"}]},{"file":"/var/www/nextcloud/htdocs/lib/base.php","line":1091,"function":"match","class":"OC\\Route\\Router","type":"->","args":["/apps/dashboard/"]},{"file":"/var/www/nextcloud/htdocs/index.php","line":25,"function":"handleRequest","class":"OC","type":"::","args":[]}],"File":"/var/www/nextcloud/htdocs/lib/private/URLGenerator.php","Line":252,"message":"image not found: image:default-app-icon webroot: serverroot:/var/www/nextcloud/htdocs","exception":{},"CustomMessage":"image not found: image:default-app-icon webroot: serverroot:/var/www/nextcloud/htdocs"}}

Additional info

No response

Start with lib/private/NavigationManager.php and lib/private/URLGenerator.php, then reproduce the failure using a generated app whose appinfo/info.xml omits the navigation icon. Trace how the default icon path is resolved. Done means an enabled app without that optional entry loads the usual web interface without a runtime exception.