Upgrade questions

What features from Lion will be lost when upgrading to Mountain Lion?
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Is it possible to update any iOS 6 device to iOS 6.1.6?
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What is happening when my Mac is being optimized after an OS X update?
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How do I change Software Update server to official one on OS X Lion (or later)?
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Can I solder more memory into my MacBook Air?
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Will Mountain Lion make an older computer run faster or slower?
macos upgrade performance
Where does the upgrade to macOS Catalina move root "/" directory files?
macos upgrade catalina
Downgrade a Mac App Store app?
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What's the best way to update Homebrew when upgrading macOS?
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Can I use the new Lion OS X license on two machines, or do I have to buy one for each?
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How to fix "macOS needs to repair your library to run applications" after High Sierra upgrade?
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Using memory with a higher MHz rating?
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Can I restore an iPhone backup taken from a previous iOS version, or is there a better way to retain my data?
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How do I upgrade git on Mac OS X?
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Solder new RAM in a 2015 Retina MacBook Pro
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Changing SSD's and keeping everything
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How long can I expect my system to be unusable during an upgrade to OS X Lion?
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How can I remove the Parallels icons from Launchpad in Lion?
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Why do macOS/iOS upgrades take so long?
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How to update some application to latest version with homebrew-cask?
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