Mojave and Safari 14. Don't go there.

[BobShaw]

Just be aware that if you are using Mac OS Mojave do not update Safari to version 14 or use the Supplemental Update that does the same thing. You will lose all ability to upload photos to any website.
The only way to fix it is to do CMD-R and reinstall the OS or do a complete restore from backup.

Affects MacOS Mojave 10.4.6 / Safari 14.0.1

Safari 14 apparently is fine on Catalina.
This is not the same problem as the "crashing Safari".

[Joe Towner]

Do you use TimeMachine?  You should be able to roll back Safari fairly easy to the previous build, or swap browsers for a few days. I see all the posts, I expect that Apple will resolve this asap.

-Joe

[bobfriedman]

now you tell me. I just found this out. ohhh well.

[kers]

I like Firefox better anyway- maybe an alternative?

[bobfriedman]

I will upload with Chrome until they fix this.

[langier]

Other than the Facebook glitch for uploading some albums, I've haven't had much issue in uploading from my vintage 2009 MacPro to the web using Mohave and Safari 14.

[BobShaw]

Do you use TimeMachine?  You should be able to roll back Safari fairly easy to the previous build, or swap browsers for a few days. I see all the posts, I expect that Apple will resolve this asap.

Yes, I use Time Machine (each hour). My problem was that I did not become aware of the problem until a week or so later. I could have rolled back to that point but would have lost a fair bit of work (mail etc). My first effort was to just drag and drop the old Safari onto the new, but that doesn't work. You get a warning that Safari is part of the Operating System and can not be changed. Reinstalling the OS from CMD-R did not lose any work and would have been much quicker than a complete restore of the hard drive.

You can then reinstall the Security and Supplemental Updates but not Safari 14.0.1

[Manoli]

Just be aware that if you are using Mac OS Mojave do not update Safari to version 14 or use the Supplemental Update that does the same thing. You will lose all ability to upload photos to any website.
Affects MacOS Mojave 10.4.6 / Safari 14.0.1

I'm running both Mojave (10.14.6) and Safari 14.0.1.
I have no such problem.

Is there an Apple Support advsory on this ?

[BobShaw]

I'm running both Mojave (10.14.6) and Safari 14.0.1.
I have no such problem.

Is there an Apple Support advsory on this ?

I haven't seen anything from Apple, but it is all over the Apple Support Community. It is possibly something to do with the security update. I am also having trouble installing apps.
https://discussions.apple.com/thread/252051818

All I can suggest is that you test uploading immediately after the update and if there are issues straight away restore to the backup just before.

[BobShaw]

It looks like the problem was Security Update 2020-005 coupled with the Safari 14 update.
Apple pulled both updates just after they were released and re-issued them a couple of days later with the same names.
It may be OK now but do a Time Machine backup at each step and fully check after update.
Each time you update you see more updates.

If you got trapped to recover you can do a clean instal of the OS using CMD-R and you go back to Safari 12.