[padilha007]

exist one way to prevente this error?

[Exolent[jNr]]

That is caused by using message_begin(MSG_ONE[_UNRELIABLE], ..., ..., entity) where entity is not a valid entity.
To fix it, all you have to do is make sure that entity is valid, (if it is a player, would be best to check if is_user_connected()).

[padilha007]

check class of entity should be correct to help?

[joaquimandrade]

Originally Posted by padilha007 check class of entity should be correct to help?

Exolent means is_valid_ent or pev_valid. Retrieve the class of an invalid ent wouldn't work.