ActiveCampaign server related issues (regular running licence)

Hi everybody, I have a regular licence running with ActiveCampaign software (Version installed on my server Linux Centos 64bit). One week ago, upgrading to the latest version (version 12all_I_5.4.0_build59) software started giving several problems. Here are the most import: - If I try to send a test mail (Account > Your Setting > Mail Sending) this gives several errors - If I try to send a mailing (for exaple I create a “Test List” with 1 or 2 subscribers and then try to send a campaign: software stalls in "preparing subscribers" even if subscribers are only 2 Also if I connect to my Admin Pannel there is something not working properly: >>> see the attached image -------------- I contacted ActiveCampaign Support and today they answered me: "Sorry for the delay. It looks like the issues are server related. Unfortunately, that is beyond the scope of support. I suggest contacting your server admin." -------------- I need to check related server setting and make running properly the software. For any question please contact me. Thanks, Johnny