I think you are logged in with two gmail account: That is why (/u/1,/u/0) may have been appended to script address (may be a bug).
So what you have to do is remove /u/0 or whatever is appended.
ForExample:
https://script.google.com/macros/u/1/s/ffffsdds/exec becomes https://script.google.com/macros/s/ffffsdds/exec