Server preview is not working

Suddenly the server preview is not working anymore.
Any suggestions how I can solve that?
Thank you very much!

PS: I am using the “custom loader”. It has added a “load” to the URL. Does I have to change the server_url in the Google Tag now? Or somewhere else? In the App?

No. it’s only for js load optimization.

What error do you see? what is your container identifier?

now it is working again without changing anything…
but thank you very much!