While running the flow engine gui, these error messages show up after saying Par is done.
Error: rpc server is unavailable Error: the object invoked has disconnected from it's clients.
The problem is not well understood at this time, but appears to be due to the design manager losing contact with a process that it is running.
Workaround: If problem occurs frequently, an alternative is to run the M1 tools from command line.
One possible cause for this error is that the user's PC is configured to use a network card, but is not able to. This could be caused by the network card being removed or installed incorrectly. To solve this, correctly install a network card into the system.
Please make sure that you have free disk space available on your hard drive. Lack of hard drive space is one reason this error has occured.
Create a new project in design manager with same files. The old project may have gotten corrupted somehow.