AH00161: server reached MaxRequestWorkers setting, consider raising the MaxRequestWorkers setting

Basically config got overwritten in: /etc/apache2/mods-available/mpm_prefork.conf

I put the new setting in that file and it seems Apache works correctly now.

Hopefully this helps someone else, don't put your config straight in apache2.conf or httpd.conf. Make sure you change all loaded config files.

you should edit mpm_prefork

<IfModule mpm_prefork_module> StartServers 10 MinSpareServers 10 MaxSpareServers 20 ServerLimit 2000 MaxRequestWorkers 1500 MaxConnectionsPerChild 10000 </IfModule>

You modified the wrong file. Your log says "mpm_prefork" error. So you need to modify mpm_prefork.conf rather than mpm_worker.conf.

You can also use "apachectl -M" to see what module you are using. e.g. My apache2 is using mpm_event_module, so i need to modify mpm_event.conf

$ apache2ctl -M
Loaded Modules:
 core_module (static)
 so_module (static)
 watchdog_module (static)
 http_module (static)
 log_config_module (static)
 logio_module (static)
 version_module (static)
 unixd_module (static)
 access_compat_module (shared)
 alias_module (shared)
 auth_basic_module (shared)
 authn_core_module (shared)
 authn_file_module (shared)
 authz_core_module (shared)
 authz_host_module (shared)
 authz_user_module (shared)
 autoindex_module (shared)
 deflate_module (shared)
 dir_module (shared)
 env_module (shared)
 filter_module (shared)
 mime_module (shared)
 **mpm_event_module (shared)**
 negotiation_module (shared)
 setenvif_module (shared)
 status_module (shared)
 wsgi_module (shared)