In MikroTik 5.8 if I apply the command The print command shows me: And in MikroTik 5.12 if I apply the command, the print command shows me: That means set-bgp-prepend-path="" is new here. What should I dow for this? Please help me as I am not expert.

p.s. in 5.8, my configuration is perfectly working. But same command in 5.12 is not working.

Try this:

You will need to get the line number from a print.

/routing filter unset (line number) set-bgp-prepend-path

thanks.