helloIm having trouble with my iPhone 6 tried to update & restore from i tunes keeps showing error 9. my mac is updated ? any suggestions

What mac os is running on the mac curently?

I'd try their suggestions

If you see error 9, 4005, 4013, or 4014 when you restore your iOS device - Apple Support

the latest mac os is Mojave 10.14.6

so Yours itunes on high sierra is not up to date.Update to Mojave if You can if no use an other pc with latest itunes version.

You are welcome.I think that Yours Iphone is on curent IOS 12.x and this IOS can not be handled by older Itunes version.