Some Galaxy Note 8 users are unable to connect to mobile networks after installing the July 2020 Android security patch
As the name suggests, security updates are meant to keep a smartphone secure against security exploits. However, they are known to break more things than they fix on more than one occasion. Samsung Galaxy Note 9 users found that out the hard way, when the phone's display started going haywire after the March 2020 Android security patch. The Galaxy Note 8 is the latest victim of Samsung's shoddy software updates.
Piunikaweb stumbled upon a bunch of users who have been unable to connect to mobile networks on their Galaxy Note 8 after installing the July 2020 Android security patch. Some users say that their devices display a 'No SIM Card' error while others state that they see a 'no IMEI number' message. To make matters worse, the SIM card manager within the Settings app doesn't seem to be working either. The update may have messed with the phone's EFS partition, as all the SIM card and IMEI-related information of a device is stored there. One potential solution is to downgrade the Galaxy Note 8's firmware to an earlier version using ODIN. Do this only if you're familiar with how ODIN works and have used it earlier.
However, the problem won't go away for most users without Samsung's intervention, as regular troubleshooting steps don't seem to have any effect. At the very least, Wi-Fi connectivity is unaffected, allowing users to download any fix that Samsung issues. It appears that only Indian variants of the Galaxy Note 8 are affected. However, we recommend that you don't install the update on your device until Samsung issues an official statement.