"The login is invalid" error logging into cPanel from WHM

Symptoms

Logging into a cPanel account via "List Accounts" in WHM can sometimes return the following error.

The login is invalid.

Description 

This error is often an issue with the browser cache. You can try reproducing the error in another browser or a "private/incognito" window to verify this. If the error is not present, clearing the browser cache on the browser experiencing the issue should resolve it.

If the error occurs on multiple devices, stale cached userdata files may contain outdated information preventing the logins from proceeding.

Workaround

The following article contains instructions on how to clear the cache on the most common browsers:

How to Clear your Browser's Cache

If you find this occurring on multiple devices, then some cached userdata files may still contain a reference that the account in question is "Suspended." You can clear this data by suspending the account and unsuspending it immediately:

How to Suspend or Unsuspend an Account.