I have an unlocked note 9 on t-mobile. I have had luck getting rid of the 407 message until next restart doing the following:
1. Turn off phone
2. Take out sim
3. Turn on phone
4. After phone loads, insert sim.
I don't get the hourly message that firmware upgrade failed anymore. But last time I restarted my phone it came back. I don't restart too often, so it's longer relief than any of the other "solutions" offer.
I am having the same issue. I contacted Samsung support and they said to take it to my local Ubreakifix store and have them take a look at the software, so I did but they couldn't fix it, so now what? I'm so disappointed at Samsung support that now I am seriously thinking of going back to iPhone, as a previous iPhone user I can say that apple has superior customer service.
2+ months later and no solution is really disappointing. I ordered a free sim card from giffgaff just now since others have said that is a possible solution. I don't have an extra laying around.
Here is a fix that worked for me:
SCROLL DOWN TO THE ANSWER BY "hunter2451". Follow the instructions to delete the app and it will work.
Ok. That is what fixes it. I tried the SIM card I got that wasn't t-mobile, but that didn't help either. For this solution, I only was able to execute the first command. The other came back as "not installed". But the steps I did:
Download adb here, then install on C:\ on a Windows PC
turn on USB debugging in developer options in settings on my s10e
open cmd on my PC, then:
pm uninstall -k --user 0 com.sec.omadmspr
It says "Success", and reboot the phone and the error is gone. If you check apps and turn on system apps, there's no OMADM or Sprint OMADM app as you scroll down anymore. Thanks.