scoreboard is full, not at MaxRequestWorkers.Increase ServerLimit.
We just experienced these bugs , after upgrading to apache 2.4.43 /directadmin/centos7 which cause the webserver to freeze , and we have to restart the httpd service .
After searching for a while , we know that these are bugs in Apache as stated in here
Some people in StackOverflow and Serverfault recommend to increase by setting MaxSpareThreads = MaxRequestWorkers. , but the server load everage rose after that , so in other threads said about to set MaxConnectionsPerChild to 0 or comment it out (mpm_event.conf).
This last method had lessened the problems , so lets try .