Yesterday my OAuth2 configuration against my sandbox was working just fine.
Today it stopped working and I am receiving:

• error = invalid_client_id
• error_description = client identifier invalid

I was running the OAuth2 request via curl (http://en.wikipedia.org/wiki/CURL) without any issues for days and suddenly it is just not working.

curl https://test.salesforce.com/services/oauth2/authorize?response_type=code&client_id=MYCLIENTID&client_secret=MYCLIENTSECRET&scope=full&redirect_uri=https%3A%2F%2Flocalhost%3A8443%2Fsalesforce%2Foauth2%2Fcallback&display=page&prompt=page

I tried switching to my specific pod inthe URL (https://csXX.salesforce.com) and did not have any luck.

I am attempting to work with the oAuth example at:
https://github.com/jamesward/hello-java-spring-force_dot_com/

The application builds and launches just fine.  However, when I click the provided "Contact List from Salesforce.com" link I wind up getting the following error:

Yesterday my OAuth2 configuration against my sandbox was working just fine.
Today it stopped working and I am receiving:

• error = invalid_client_id
• error_description = client identifier invalid

I was running the OAuth2 request via curl (http://en.wikipedia.org/wiki/CURL) without any issues for days and suddenly it is just not working.

curl https://test.salesforce.com/services/oauth2/authorize?response_type=code&client_id=MYCLIENTID&client_secret=MYCLIENTSECRET&scope=full&redirect_uri=https%3A%2F%2Flocalhost%3A8443%2Fsalesforce%2Foauth2%2Fcallback&display=page&prompt=page

I tried switching to my specific pod inthe URL (https://csXX.salesforce.com) and did not have any luck.

I am attempting to work with the oAuth example at:
https://github.com/jamesward/hello-java-spring-force_dot_com/

The application builds and launches just fine.  However, when I click the provided "Contact List from Salesforce.com" link I wind up getting the following error: