308 Permanent Redirect
Meaning
The resource has been moved to a new URL permanently, and future requests should use the new URI. Like 301, but it does not allow changing the HTTP method.
When to Use
When permanently redirecting a resource to a new URL while instructing clients to use the same HTTP method for subsequent requests (no method change, ensuring POST remains POST, etc.).
Example
An API endpoint's path is changed; the old endpoint responds with 308 Permanent Redirect and a Location header to the new URL. Clients will use the new URL going forward with the same HTTP verbs.
When Not to Use
Do not use if the redirect is temporary (use 302 or 307) or if allowing the HTTP method to change is acceptable (301 might be used, though 301 is often misused by clients to change to GET).
Source
RFC 7538