How do I stop the error, Authorisation is required to perform that action in Google Script

I keep getting this error message (Authorisation is required to perform that action) when I try to view my deployed app.

What I want to know is what I must to do to get around the error.

Services in use in the script: - ScriptDB - UiApp

(I think that is all)

I'm fairly sure this is a pretty stupid question, but I can't seem to find the answer in the documentation, so I would be very grateful for some help from you guys.

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You need to go the script editor and attempt to run any function manually first.

A first authorization popup is shown when you first deploy as web app, but if you go and change the code accessing new services you have to re-authorize it.

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