Es waren keine Quelldateien vorhanden, die von Photoshop geöffnet werden könnten.

Since you posted in the install forum you need to read this

Cloud Manager to install all programs https://www.adobe.com/ie/creativecloud/desktop-app.html
-https://community.adobe.com/t5/get-started/how-to-activate-your-adobe-software/td-p/9636861?page=1

Please give us more informations including the following :

Adobe product and version number

Operating system and version number

The full text of any error message (s)

What you were doing when the problem occurred

Screenshots of the problem and/or error messages

Computer hardware, such as CPU; GPU; the amount of RAM; etc