404 NOT_FOUND "Failed to validate form source due to: "; nested exception is org.springframework.web.server.ResponseStatusException: 404 NOT_FOUND
When day2 action call is made from the machines DataGrid, the parameter deployment ID provided is empty due to which request fails to retrieve actions and throws 404 error.
A resolution is in the HotFix for the 8.18.1.
Info how to find and install the fix you can find here: SolutionDetails - Support Portal - Broadcom support portal
Workaround: Users are requested to request the day 2 actions directly from deployment page in the UI OR go to Service Broker-> Deployments.