template stuck in status "creation failed" -> unusable

hello,

I have a template stuck in status: "creation failed".
I can't edit or use it.
Error message is:Source Template xyz is not in a valid state. Select a template that is in a valid state. ID 697
But it does not tell me how to get it into a valid state :(
I already deleted the VM that resulted from the creation status and also was in a failed status ofc.

How do i get the template to work again?

thanks!