Sorry to hear you’re facing problems 
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In order to help you as quickly as possible, before clicking Create Topic please provide as much of the following as you can (you can cut and paste this into your topic):
Nextcloud version (eg, 10.0.2): 11.0.4
Operating system and version (eg, Ubuntu 16.04): Webhoster 1und1
Apache or nginx version (eg, Apache 2.4.25):
PHP version (eg, 5.6): 7.1.8
Is this the first time you’ve seen this error?: Yes
Can you reliably replicate it? (If so, please outline steps): Yes
The issue you are facing:
If I want to log in with SSH and convert my database, I get the following error message.
I have no own server, only one webspace with my Provider 1und1.
Here’s the string:
php occ db:convert-type --all-apps --password="" --port=“3306” mysql dbo69540 db69540**.db.1and1.com nextcloud
And that is the error message:
X-Powered-By: PHP/4.4.9
Content-type: text/html
Fatal error: main() [function.require]: Failed opening required '__DIR__/console.php' (include_path='.:/usr/lib/php4.4') in /homepages/3/d330966295/htdocs/nextcloud/occ on line 11
The output of your Nextcloud log in Admin > Logging:
The output of your config.php file in /path/to/nextcloud (make sure you remove any identifiable information!):
The output of your Apache/nginx/system log in /var/log/____:
Remember, this information may be requested if it isn’t supplied; for fastest response please provide as much as you can 
Feel free to use a pastebin service, otherwise log files can be indented with 4 spaces on each line to present them in a friendlier way on the forum.