InformationYou should verify that the TLS CA certificate file (the file that is passed along with the --tlscacert parameter) has permissions of 444 or is set more restrictively.
The TLS CA certificate file should be protected from any tampering. It is used to authenticate the Docker server based on a given CA certificate. It must therefore have permissions of 444, or more restrictive permissions to ensure that the file cannot be modified by a less privileged user.
SolutionYou should execute the following command:
chmod 444 <path to TLS CA certificate file>
This sets the file permissions on the TLS CA file to 444.
By default, the permissions for the TLS CA certificate file might not be 444. The default file permissions are governed by the operating system or user specific umask values.