I am following the hello world here:
https://developers.google.com/apps-script/guides/rest/quickstart/target-script
Then I update the script with new featu
The Execution API will use the currently published version of your script if devMode is false or omitted from the request. What I am suspecting is that there was a change of OAuth scopes in your script. The users's OAuth token needs to include all the scopes your project requires.
Open your project's properties and click on the scopes tab. Make sure your java client's OAuth scope request matches what is in the list. You may have extra scopes in your client, but you need to at least include all that are in that list.
Also in the Execution API deployment dialog there is an option limiting access to yourself, your domain, or anyone. Make sure the the user account you are using on the client matches your choice.