Errors appeared after migrating from debian8 to ubuntu18.04

[avgaz]

Good afternoon, changed VDS from debian8 on ubuntu18. 04 at one provider, those. characteristics of iron a little also improved panel ISPmanager.
The settings are the same as they were that is in the configs in the configuration changes which were on debian8 but the site error log is teeming with such errors
php as FastCGI (Apache)+nginx

error.log

[Sat Dec 07 17:54:08.909860 2019] [fcgid:warn] [pid 28920] (32)Broken pipe: [client 91.****:54532] mod_fcgid: ap_pass_brigade failed in handle_request_ipc function, referer: https://www.******/forum/topic/****/

At the same time, an error 500 is logged in access.log

**** - - [07/Dec/2019:17:54:08 +0300] "GET /forum/topic/*****/ HTTP/1.0" 500 21888 "https://www.******/forum/topic/****/" "Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:71.0) Gecko/20100101 Firefox/71.0"

 

Settings /etc/apache2/mods-available/fcgid.conf tried different but the error does not disappear, at the moment the settings are

<IfModule mod_fcgid.c>
  FcgidProcessLifeTime 300
  FcgidMaxProcesses 3000
  FcgidMaxProcessesPerClass 500
  FcgidConnectTimeout 300
  FcgidIOTimeout 3600
  FcgidBusyTimeout 3600
  FcgidMaxRequestLen 104857600
  <IfModule mod_mime.c>
    AddHandler fcgid-script .fcgi
  </IfModule>
</IfModule>

 

I tried such settings, there is no result

 

FcgidInitialEnv PHP_FCGI_MAX_REQUESTS 3000
 FcgidMaxProcessesPerClass 3000

I suppose the error was caused by asynchronous AJAX requests on the page, since it is not visible on the page when visiting, but it is recorded in the access.log