Hi @Denis_Coulet welcome to Zwift forums.
Shuji at ZwiftHQ here. I looked at the session logs for your last successful session on January 30 and compared them to the next failed session on Feb 13. I’m seeing a Mac Pro 5 in both cases, so I’m assuming that is your preferred computer for Zwifting.
On January, that machine was running OSX Sierra v10.12 and the Zwift game app was version 1.0.44575.
On February 13, that machine had been upgraded to OSX Mojave v10.14 and Zwift game app v1.0.45663 (still the current game version). Apple’s changes to app permissions on Catalina can also trip up users running Mojave. Please have a look through the link that Mike posted and try the steps I outline there. Would you let us know how that works out?
Also - is your Mac Pro capable of being upgraded to the new-new OSX version 10.15.x? If it is, please upgrade to Catalina.