Customize fails after server change

i have changed the server of my blog and now it is impossible to customize my Sydney theme. Every time when i go to the customize link

i see this blank page:

If i try this with a standart theme it works perfectly. I have deleted the complete theme and the folder and installed new but the same problem.

Have anyone a solution for me?

Best regards, Patrick

Hello there,

I am sorry you have run into issue.

Could you please share the working login credentials to your site admin area, so I can take a closer look directly from there? For security reason, please send them privately to and mention the link to this thread.