I was trying to connect an old phone that I use to test apps on older API versions. Today adb was not finding it.
After trying pretty much everything here, I figured out that the phone was not even showing the system notification about the USB connection going on.
So I looked around for that issue, and found the solution here (credits to the original source):
- Remove phone from PC and remove battery to shut off phone.
- Plug USB cable into PC.
- Plug USB cable (other end) into phone.
- The PC install new hardware appropriate drivers for a few minutes (phone without battery)
- Unplug USB cable from phone
- Put battery back in and turn on phone
- As the phone boots, hold down Volume up and down. Phone boots into safe mode.
- Plug USB cable into phone.
- I saw notification about USB MTP-connecting on the phone. PC have found my phone!
- After the reboot in normal mode problem was fixed
Not sure step 4. is of any use here on macOS, however I did all the steps and it worked well.