Update Numbers App

You haven't said what version of OS X or macOS you are using but I will venture a guess that it is Sierra, 10.12.x or earlier. Numbers 6 as well as Pages 8 & Keynote 9, the only versions available in the Mac App Store, require High Sierra, macOS 10.13.6 or Mojave, macOS 10.14.x. You need to update the OS before you can update the apps.

It's a DIY project. First, before any upgrade, especially a system upgrade, make sure you have a current back up. Then go to the Mac App Store on your Mac & the first thing you should see at the top is something like this. (This screenshot is from Mavericks, but Yosemite should look similar.). Click the big picture & follow the onscreen directions.

rykijaarcllaca7 writes:

"I can no longer use Numbers."l

Hv =e you tried using Numbers since first seeing the message? What have you seen that leads you to the conclusion that (you) "can no longer use Numbers"?

"It is asking me to update the App…"

Is it? Or is it telling you there is an update for numbers available?

"… but it won't upload."

Does it present a message when 'it' won't upload'?

What is that message?

What version number of Numbers do you have currently installed? (Numbers menu > About Numbers…)

What version number of OS X or macOS do you have installed? (Apple menu > About this Mac…)