You do not have permission to call openById

Question

Problem: When I run the script, Google tells me,

You do not have permission to call openById

I had copied a script from anothe

Answer 1

I found this official note which I believe clears up what caused the issue.

If your function is a custom function, that is one which can be used like a regular spreadsheet function in the sheet itself, then it has limited access to things and cannot open other spreadsheets.

The same script can however open other spreadsheets from a menu button or similar.

Link: Documentation at developers.google.com