ERROR: [2] bootstrap checks failed
[1]: max file descriptors [4096] for elasticsearch process is too low,   increase to at least [65536]

Reason: Generally, you can check whether the following nodes are present in the elastic.yaml configuration file in the es installation directory

elsearch soft nofile 65536
elsearch hard nofile 65536

If not, then you need to configure it, and replace the elsearch with your own server user.

There is also a possibility that the above error is still reported even though the server has been configured, possibly due to the fact that the current logged-in user has not synchronized the configuration due to a server reboot.
Use su ~ xx to re-login to solve the problem.