Steps to reproduce:

1. Have system.swap.size[,free] item for an active agent on Linux
2. Update the agent from version 5.0.5 to 5.0.8 (server is on 5.0.8)

Result:

Zabbix agent starts logging in /var/log/zabbix/zabbix_agent.log:

898:20210130:210026.099 active check "system.swap.size[,free]" is not supported: Cannot be calculated because swap file size is 0.
898:20210130:210026.099 active check "system.swap.size[,pfree]" is not supported: Cannot be calculated because swap file size is 0.

This happens every two minutes (maybe system configuration-dependent interval).

Expected:
No errors logged in agent log file even though there is no Linux swap configured. The errors were not logged before upgrading the agent from 5.0.5 to 5.0.8.