Why is my app-console-generated access token expiring? - dropbox-api

Question

Using the App Console, I am generating an Access Token for use by my java application.
Why is my access token expiring? It worked yesterday but today I get the below error.
How do I get a permanent token for my application to use? (Usage is similar to a "Google Service Account" that generates a permanent token.)
Exception:
InvalidAccessTokenException
{
"error_summary": "expired_access_token/...",
"error": {
".tag": "expired_access_token"
}
}
UPDATE 2022 12 02:
Thanks for the below information and links. After about 5 hours of working on wrapping my brain around the concepts and the example code, I finally got something working by doing the following:
(1) Using the example code and manual process at https://github.com/dropbox/dropbox-sdk-java/blob/main/examples/examples/src/main/java/com/dropbox/core/examples/authorize/ShortLiveTokenAuthorize.java I obtained an auth code.
(2) I then wrote java code to post the auth code to the https://api.dropbox.com/oauth2/token end point and receive tokens including the refresh token.
(3) I then wrote code to post the refresh token to the same end point to receive an access token.
It appears I can hold on to the refresh token and repeat step 3 to get access tokens each time.
HOWEVER, I must be missing something here.
This is WAY too much extra work that should be done either by the App Console and/or the SDK.
Also, it seems to me that a “Client Credentials Flow” should be available in the API and SDK.
Your thoughts?

Answer 1

Dropbox is in the process of switching to only issuing short-lived access tokens (and optional refresh tokens) instead of long-lived access tokens. You can find more information on this migration here.
Apps can still get long-term access by requesting "offline" access though, in which case the app receives a "refresh token" that can be used to retrieve new short-lived access tokens as needed, without further manual user intervention. You can find more information in the OAuth Guide and authorization documentation.
The official Dropbox Java SDK can actually handle the process for you automatically, as long as you supply the necessary credentials, e.g., as shown retrieved in the examples here.