WAS FACING SAME ERROR. I AM ON LATEST SUPPORTASSIST. 3.4.1.49. ON INSPIRON 5490 SUPPORTASSIST SHOWING UNEXPECTED ERROR IN DRIVER AND DOWNLOAD. WEB SUPPORT SHOWING 1 DOWNLOAD AVAILABLE. WHICH WAS NOT DOWNLOADING. I UNINSTALLED SUPPORTASSIST UPDATE PLUGIN FROM CONTROL PANEL. RESTART THE SYSTM. ALL WORKS FINE NOW.
it tells me it ran into an unexpected issue and to restart my pc which i have done several times to no avail.                
support assist unexpected error