How can I update my MacBook Pro to version 10.14.6?

Compatibility may be the Culprit:

I you are trying to upgrade from High Sierra-to-Mojave, then go to the below link to verify if your Mac is even compatible with Mojave. If it is incompatible, then it is incompatible. Therefore, upgrading to Mojave would not be an available option to you.

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How to Verify:

1. Find your Model:

To find your model, go to: Apple Menu > About this Mac... > Overview tab > View the third line down

2. See if it is Shown here:

1. Go Here: How to Upgrade to macOS Mojave - Apple Support
2. Screenshot: Mojave-Compatible Devices

Hello, i take it you are new into the apple community or have never needed to update anything, besides that go into System preferences > Software Update and update to the version that it shows you which should be the latest version availible of High sierra, if its the correct version you need if not , and you need an older version of macos please refer to this article from apples support website https://support.apple.com/en-us/HT211683 . 🙂 If you have any further questions just reply to this Hope it works for you!