there's no harm in doing something

there is no harm in (someone's) doing (something)

Doing something may be good, pragmatic, or beneficial, and will not cause any problems or harm. The contractor might not be willing to go any lower on the price, but there's no harm in asking. Sure, you might not be accepted for the PhD program, but there's no harm in your trying, is there?
See also: harm, no, there
Farlex Dictionary of Idioms.

there's no harm in doing something

COMMON People say there's no harm in doing something to mean that it will not cause problems and may have a good result. They are not always willing to take on untrained workers, but there's no harm in asking. As I see it, there is no harm in cooperating with the police.
See also: harm, no, something
Collins COBUILD Idioms Dictionary, 3rd ed.

there’s no harm in (somebody’s) doing something

,

it does no harm (for somebody) to do something

used to tell somebody that something is a good idea and will not cause any problems: He may say no, but there’s no harm in asking. It does no harm to ask.
See also: harm, no, something
Farlex Partner Idioms Dictionary
See also:
  • (I) hope not
  • hope not
  • not for a second
  • not for a minute
  • not for a moment
  • aint
  • ain't
  • be not much cop
  • not for a instant
  • not for a/one minute/moment/second/instant