Hi there,
The issue you are facing:
I was hoping someone might have encountered a smiliar issue, as the one displayed above, when trying to download metadata.xml for SAML SSO.
The only special about this nextcloud instance is, it is a fresh install but with migrated data from our old instance. So new VM + OS but same database + data directory.
The logs suggest that - as far as i think i understand it - is something like it can’t find the SSO SAML app as it might be searching for it in the directory it was on the old instance. So just a wrong path…
Using the Add-Ons I encountered some Problems and I had to deactivate and later on activate them again to get them to work.
But it seems I can’t get the SAML SSO one to properly work.
The Theming background picture also seems to be missing but that propably isn’t the same issue as the error i enounter when trying to download the metadata.xml.
Is this the first time you’ve seen this error? (Y/N) : First time since migrating the Cloud Instance
Steps to replicate it: Go to Admin Settings > SSO & SAML Authentification > Generate Metadata.xml
The output of your Nextcloud log in Admin > Logging :
[index] Error: OCP\App\AppPathNotFoundException: Could not find path for spreed at <<closure>>
0. /srv/www/htdocs/nextcloud/core/Controller/SvgController.php line 99
getAppPath("spreed")
1. /srv/www/htdocs/nextcloud/lib/private/AppFramework/Http/Dispatcher.php line 166
getSvgFromApp("spreed", "app-dark", "000")
2. /srv/www/htdocs/nextcloud/lib/private/AppFramework/Http/Dispatcher.php line 99
executeController(OC\Core\Controller\SvgController {}, "getSvgFromApp")
3. /srv/www/htdocs/nextcloud/lib/private/AppFramework/App.php line 118
dispatch(OC\Core\Controller\SvgController {}, "getSvgFromApp")
4. /srv/www/htdocs/nextcloud/lib/private/AppFramework/Routing/RouteActionHandler.php line 47
main("OC\\Core\\Controller\\SvgController", "getSvgFromApp", OC\AppFramework\ ... {}, {app: "spreed",f ... "})
5. <<closure>>
__invoke({app: "spreed",f ... "})
6. /srv/www/htdocs/nextcloud/lib/private/Route/Router.php line 297
call_user_func(OC\AppFramework\ ... {}, {app: "spreed",f ... "})
7. /srv/www/htdocs/nextcloud/lib/base.php line 987
match("/svg/spreed/app-dark")
8. /srv/www/htdocs/nextcloud/index.php line 42
handleRequest()
GET /index.php/svg/spreed/app-dark?color=000&v=1
from 10.195.24.131 at 2020-04-16T08:58:55+00:00
The output of your config.php file in /path/to/nextcloud (make sure you remove any identifiable information!):
<?php
$CONFIG = array (
'instanceid' => 'oc2jos7cwk92',
'passwordsalt' => 'XXXXXXXXXXXXXXX',
'secret' => 'XXXXXXXXXXXXXXXXXXXXXXXXXX',
'trusted_domains' =>
array (
0 => 'XXXXXXXXXXX',
1 => 'XXXXXXXXXXX',
2 => 'XXXXXXXXXXX',
),
'datadirectory' => '/srv/www/htdocs/nextcloud/data',
'overwrite.cli.url' => 'XXXXXXXXXXX',
'dbname' => 'nextcloud',
'dbhost' => 'localhost',
'�dbport�' => '�3306�',
'dbtype' => 'mysql',
'version' => '15.0.12.1',
'installed' => true,
'updater.release.channel' => 'stable',
'maintenance' => false,
'theme' => '',
'loglevel' => 'debug',
'dbuser' => 'root',
'dbpassword' => 'XXXXXX',
'ldapIgnoreNamingRules' => false,
'forcessl' => false,
'mail_from_address' => 'cloud',
'mail_smtpmode' => 'smtp',
'mail_domain' => 'XXXXX',
'updatechecker' => false,
'has_internet_connection' => true,
'ldapProviderFactory' => 'OCA\\User_LDAP\\LDAPProviderFactory',
'mail_sendmailmode' => 'smtp',
'mail_smtpauthtype' => 'LOGIN',
'mail_smtpauth' => 1,
'mail_smtphost' => 'XXXXXXX',
'mail_smtpport' => '25',
'mysql.utf8mb4' => true,
'memcache.local' => '\\OC\\Memcache\\APCu',
'session_keepalive' => false,
'session_lifetime' => 600,
'remember_login_cookie_lifetime' => 0,
);
The output of your Apache/nginx/system log in /var/log/____ :
Really no valuable information about this Problem in the Apache Logs
Cheers 
