While exporting a very tiny number of objects to FIM, the export operation gave a stopped-server error and the Event Viewer for FIM reported the “export session has timed out”. It rambled on a bit about connection times taking too long, resetting the timeout value, etc.

After failed attempts to fix this by rebooting the FIM Sync Server, clearing out the metaverse, etc. the solution turned out to be blindingly obvious–restart the FIM Service.