This errors says your function is already defined ; which can mean :
- you have the same function defined in two files
- or you have the same function defined in two places in the same file
- or the file in which your function is defined is included two times (so, it seems the function is defined two times)
To help with the third point, a solution would be to use include_once
instead of include
when including your functions.php
file — so it cannot be included more than once.