Unable to start Linux (CentOS 7.9) connector

You get the following error when you start the connector:

Job for td-agent.service failed because the control process exited with error code.
See "systemctl status td-agent.service" and "journalctl -xe" for details. 

Issue symptom

This issue might occur because the libyaml file is missing on the host computer.

Issue scope

This issue might impact all Linux (CentOS 7.9) connectors.

Resolution

Run the following command to verify whether the library is present on the host computer:

cd to  /opt/td-agent/bin/
/opt/td-agent/bin/ruby fluent-gem list

If the file is not present, you get the following output:

/opt/td-agent/lib/ruby/2.7.0/yaml.rb:3: warning: It seems your ruby installation is missing psych (for YAML output).
To eliminate this warning, please install libyaml and reinstall your ruby.

Install the libyaml-0.1.4 file on the host computer and then start the connector.

If the libyaml file is present on the host computer, it appears in the gems list. To resolve your issue, contact BMC Support.

[root@<hostname> bin]# /opt/td-agent/bin/ruby fluent-gem list

*** LOCAL GEMS ***

addressable (2.8.0)
async (1.30.2)
async-http (0.56.5)
async-io (1.33.0)
async-pool (0.3.10)