Request had invalid authentication credentials. Expected OAuth 2 access token error in cloud speech api

It could be that The Application Default Credentials are not available

Try to login by running

gcloud auth application-default login

And follow the instructions, reference: gcloud auth application-default login

If you want to make sure the authentication process went well, run:

gcloud auth application-default print-access-token

You should see an access token, reference gcloud auth application-default print-access-token

I fixed the problem by logging out, and logging in to agree to some new terms and conditions google have made since last time I used google clouds (firebase in my case).

Replace $(gcloud auth application-default print-access-token) with what gets printed when you call the command.