How to fix invalid_grant error in AdWords API?

Question

PHP

There was a problem when migrating to v201409.
No matter what I do, I get the error An error has occurred: { "error" : "invalid_grant" }
I set it up as on https://developers.google.com/adwords/api/docs/gui... but the error does not go away. Those. I created the application in the console, received a refresh token, but nothing works.
Before that, I used version v201402 and everything was good.
Please help, my eyes are on my ass already :(

Answer 1

Alternatively, I get an error:
Catchable fatal error: Argument 1 passed to OAuth2Handler::GetOrRefreshAccessToken() must be an array, string given, called in