Problem using XE2 and 10.2 parallel

I had recently installed Delphi 10.2. Ever since I get problems everytime I go back to my XE2 environment.

[DCC Fatal Error] ProjectWhatever.DPR(1): F1027 Unit not found: 'System.pas' or binary equivalents (.dcu)

Following a "bds.exe -pDelphi -rfoo" I can use my XE2 environment until the next time I start 10.2.

I never hit this problem up until 10.1.

Is there any solution or something I have missed?