Will upgrading from High Sierra cause me to lose everything on my MacBook Pro?

To put it simply- no. Your data will likely not be erased. However, there's always a chance when performing these kinds of actions, and it really doesn't hurt to have a backup, as leroydouglas explained.

Amy_in_MN wrote:

Will upgrading from High Sierra cause me to lose everything on my MacBook Pro?

I am very concerned about updating my IOS when I can't fully backup everything on my MacBook Pro. If I update the IOS, am I likely to lose anything on my MacBook (including any non-Apple programs and/or associated data)?

I have a LOT of various items/data/photos on my MacBook Pro. Some can be backed up and some cannot, at least easily (i.e. email) - and I am only somewhat tech savvy. I have used/use external drives (and Time Machine in the past) to back up documents, but I really need to update Safari and it seems that I cannot do this unless I update the IOS.

Thanks in advance for any insights and guidance!

the mac computer runs the macOS.

It is iDevices like iPhone etc run iOS...

Apple would not be in business if every time you upgrade you lose user data...(?)

You do not say what exact Mac? >About this Mac ( do not post a serial number)

what is your current exact macOS, what are you hoping to upgrade to(?)

the current stable release of your High Sierra is 10.13.6 (17G14042) November 12, 2020.

hardware/year of your mac can be a limiting factor...you do not give enough detail.

There are other browser that are more contemporary that does not have to be Safari..... ex Firefox is independent of your macOS

If you value your user data—

3-2-1 Backup Strategy: three copies of your data, two different methods, and one offsite.

more than one backup method, on more than one external device

reference:

Upgrading macOS without fear - Apple Support Communities

How to get old versions of macOS - Apple Support

> updating my IOS

The correct term is macOS.

> If I update the IOS, am I likely to lose anything on my MacBook

Not likely but that's why you should do good backups. Just in case.

Time Machine should backup all your stuff including mail. But I'd do a bootable backup to another (APFS formatted) SSD disk with Carbon Copy Cloner. And verify it really Option-boots so you can continue your work from there if something happens to go wrong. A belt and suspenders. Just in case.

Better to be safe than sorry especially since upgrading from High Sierra to Monterey is quite a big leap.

You should not lose anything, but that’s a bet you don’t want to make.

You may lose use of some of your applications.

Use Go64 to determine what won’t work anymore.