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

We'll see a new BOINC version release soon, but for now a fix is here:
https://boinc.berkeley.edu/dev/forum_th ... tid=105657

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