I've the Power BI Desktop RS Version as 1.5.7074.36177 (May 2019) and Power BI Report Server (Development version): 2.73.5586.1501 64-bit (September, 2019)
I tried to save the report to PBI RS, it is throwing following error:
We can't save this Power BI Desktop report because either it is newer version or has component parts that are not supported.
I was able to upload it previously and I'm not sure what settings have changed. It started giving the above error.