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.