Greetings from the ManageEngine Network Configuration Manager team!
Few customers around the globe reported that they are not able to access Network Configuration Manager UI with error Invalid Credentials. While checking the issue in remote sessions, we found the table which has the user details of account got empty. Few other table entries related to user mappings were also missing. Though the application is running, users were not able to login to application.
This all happened due to a minor glitch in our background handling, this has impacted user related tables for few installations which has access to internet. We have identified the root cause and fixed this permanently so that this will not repeat again in future.
In case, if you are experiencing the same issue, please contact Support referring this post so that we can help you in restoring the UI access.