Power BI Desktop (Optimized for Power BI Report Server - August 2018)

Hi Anonymous for PBIRS Microsoft only support the current release plus the two prior releases (see https://docs.microsoft.com/en-us/power-bi/report-server/support-timeline) so the Aug 18 release is no longer a supported release. If you want to keep running older releases that are out of support you need to keep a local copy of the desktop installer as Microsoft removes unsupported versions from their download servers. I know this is sometimes easier said than done, but your other option is to upgrade to a more recent release (I'd suggest trying the Sep 19 release as there are a few issues MS is working on for the latest release)