I have no idea how to find out what's causing the problem here. Especially considering that it's working for the wedding site – in the same browser, running on the same server.
There are some errors in the console after logging in:
Uncaught
Exception { name: "NS_ERROR_STORAGE_CONSTRAINT", message: "", result: 2153971715, filename: "[url=https://www.danielbollinger.de/panel/filemanager_js/x3_panel.js?v=3.30.1]https://www.danielbollinger.de/panel/filemanager_js/x3_panel.js?v=3.30.1[/url]", lineNumber: 10180, columnNumber: 0, data: null, stack: "@https://www.danielbollinger.de/panel/filemanager_js/x3_panel.js?v=3.30.1:10180:58\n" }
[url=https://www.danielbollinger.de/panel/filemanager_js/x3_panel.js?v=3.30.1]x3_panel.js:10180[/url]
Uncaught TypeError: protectPageAfter is not a function
createMtree https://www.danielbollinger.de/panel/filemanager_js/x3_panel.js?v=3.30.1:7152
show_left_folder_menu https://www.danielbollinger.de/panel/filemanager_js/x3_panel.js?v=3.30.1:9944
jQuery
[center]11[/center]
load
each
each
load
c
fireWith
l
o
send
ajax
load
show_left_folder_menu https://www.danielbollinger.de/panel/filemanager_js/x3_panel.js?v=3.30.1:9939
<anonymous> https://www.danielbollinger.de/panel/:323