There is an expired certificate in the BOINC clients that causes communication errors with several projects: Amicable Numbers climateprediction Collatz Conjecture GPUGRID iThena SiDock@home SRBase WUProp@home
WIndows BOINC client 7.16.20 has been released. This emergency update fixes communication problems with some projects and account managers. Download here: https://boinc.berkeley.edu/download_all.php