Posting array and redirecting to another page

Solution 1:

Your architecture is wrong. You should not redirect a user to another page just to show the error messages. Why cant you just show the error messages on the same page.

Consider altering your application flow. But if you insist on doing something like this then you can use sessions for this. In signup.php if validation fails

if(!validation)
{
$_SESSION["err"] = $error;
}

Then in msg.php you can access the session variable easily as

foreach($_SESSION["err"] as $err) {
echo $err;
}

But if this is what you intend to do there is much better ways to do this and consider altering your flow to do in a better way.