Please see: Kindly help me with installing an ssl certificate on my new website bsgcars.com.ng
Vesta forum has a long thread on this error: https://forum.vestacp.com/viewtopic.php?f=11&t=18597
The latest release is from April 2019: https://forum.vestacp.com/viewtopic.php?f=25&t=18599
[not sure what version you have]