Master SolusVM fails to connect to the slave node: Connection Failed Debug Data: ERROR:4

Symptoms

Master SolusVM fails to connect to the slave node: Connection Failed Debug Data: ERROR:4

SolusVM Master and slave have been updated to stable version 1.21.01

SolusVM slave server is running on lighttpd:

# netstat -tuxnlp | grep 6767

Cause

Not supported old PHP handler on the slave server. The issue can occur after upgrade to the latest SolusVM releases

Resolution

Note: The article is applicable for the cases with ERROR: 4 code error only. If the code error is different, search for the solution in this hub article

Note: If the web server is based on lighttpd software, it is recommended to switch to svmstack-nginx

1. Connect to the slave server via SSH
2. Make php alias to use SolusVM compiled PHP:

   # mv /usr/bin/php /usr/bin/backup-php

   # ln -s /usr/local/svmstack/php/bin/php /usr/bin/php

3. Switch from lighttpd to svmstack-nginx service:
   • install repository

     # yum install solusvm-release

   • shutdown lighttpd service

     # service lighttpd stop

     # chkconfig lighttpd off

   • install nginx and legacy configuration file

     # yum install svmstack-nginx svmstack-nginx-legacy-slave-config

   • start new service

     # service svmstack-nginx restart

     # service svmstack-fpm restart

   For more details check the following article

Also, the following article can be useful in case of blank page in SolusVM web interface:
SolusVM getting a blank page after the update to 1.20.09 or higher on CentOS 5 node