I've set up the whole Google Ads API according to this manual here: https://developers.google.com/google-ads/api/docs/client-libs/python/oauth-desktop?hl=en
I got my refresh token and put it in my google-ads.yaml file which looks exactly like this: https://github.com/googleads/google-ads-python/blob/master/google-ads.yaml. I also put my client_id, developer_token and client_secret at the corresponding spots in the file.
Everything worked out and I could for example ask for all campaigns: https://developers.google.com/google-ads/api/docs/samples/get-campaigns#python. Also I could use other services of the API.
Each time I use the API I access it via the client using the following code:
from google.ads.google_ads.client import GoogleAdsClient
client = GoogleAdsClient.load_from_storage(path_to_google_ads_yaml_file)
As I already said it worked.
A few days later I tried to connect again and I got the following error:
“error”: “invalid_grant”, “error_description”: “Token has been expired or revoked.”
So I did the process of getting a new refresh token again (https://developers.google.com/google-ads/api/docs/client-libs/python/oauth-desktop?hl=en) such that everything worked out again.
One day later I got the same error again. So my question is: What is the purpose of the refresh token? I thought it allows me to access the API without ever having to ask for a new token or refresh token!?
Now, I again tried to connect to the API once more (although it didn't work last time) and now I got an even worse and new error:
'invalid_grant: Bad Request', '{\n "error": "invalid_grant",\n "error_description": "Bad Request"\n}'
So things are getting even more complicated...
As @fatima Ajij pointed out, the whole issue / problem lies in the settings: Have a look at his answer: Token has expired or revoked - Google Ads Thanks a lot, fatima Ajij!