Trying to use M2M but get error 'invalid client'

AI generated answer (using internal Slack threads):

It seems like you're encountering an issue with the OAuth 2.0 Client Credentials (M2M) setup in NetSuite. The error message "Unable to retrieve access token for destination id: 1277364, name: IN - NetSuite Sandbox 2." suggests that there might be an issue with the access token retrieval process. One of the possible reasons for this error could be that NetSuite uses the assertion framework extension, which makes the client credentials setup more complicated than usual. Another possible reason could be related to the execution context. As per the second thread, there was a change in NetSuite 2025.1 where you need to set Environment Variables before being able to create a machine-to-machine based authentication. If these variables are not set, you might encounter the error "Machine-to-machine authentication is not allowed for the current execution context." To resolve this issue, you could try setting the required Environment Variables in your system. After setting these variables, you should be able to create machine-to-machine based authentication. ****** Disclaimer: This response was generated by an artificial intelligence assistant based on previous conversations from multiple Slack channels, and may contain inaccuracies or mistakes. ******