If you are unable to launch any Plesk utility from command line, it fails with error:
Access is denied. (Error code 5) at Unable to connect to pipe
For Example:
"%plesk_bin%\mchk.exe" --domain --domain-name=domain.tld
Access is denied. (Error code 5) at Unable to connect to pipe \\.\pipe\P_4a9e5d11-11f3-4cb9-8849-4d231d6cb
The above error is caused when the commands are not launched with administrative privileges, it is required admin rights for execution.
Make sure that you launch command under administrator or user with administrator privileges. Open command line (cmd.exe) as administrator (right click on "command prompt"->"run as administrator") and then execute necessary command again.