APEX - Unable to log into Application "404 Not Found"

Summary

Getting Rest Data Services "404 Not Found" error when trying to log into any of the Apex applications I have created on Autonomous Data Warehouse

Content

Hi all,

I hope you can help as this issue seems to be a fairly regular occurrence. Periodically when I try and log into my APEX applications that I have created I get the following error (see screenshot attached for full message). The login screen appears and allows me to enter my username and password but when I click the "Sign In" button I am redirected to the attached page.

404 Not Found

The procedure named null could not be accessed, it may not be declared or the user executing this request may not have been granted execute privilege on the procedure. Check the spelling of the procedure and check that the execute privilege has been granted to the caller