This could only occur if you had added a grid to the BatchPatch service instance (means you were using the run-as-service feature in BatchPatch), and then the service was stopped/disabled/uninstalled without ever removing the grid from the service instance. Then when you try to load that .bps file into the regular BatchPatch window, BatchPatch still thinks it is loaded in the service instance, so BatchPatch tries to connect to the service instance to load the file, but there is no service instance listening because it has previously been stopped/disabled/uninstalled.
The solution is to start/enable/install the service instance OR if you don’t plan on using the service instance then you may simply close all instances of BatchPatch, then delete this registry value: HKCU\Software\BatchPatch\Service\BpsFilesToLoad
Then launch BatchPatch and load the .bps file.