I am using an iPhone 6s with iOS 12.4 and a MacBook Pro mid2015 with macOS 10.14.6. Since recently (I am not exactly sure when it started), I cannot charge the phone with my computer anymore. As soon as I plug the phone in, it will play the charging sound repeatedly. The right-hand side port sometimes works, the lefthand side port never works. When I connect my old iPhone 5 (using the same cable), it charges without any issues. My iPad mini 4 shows the same issue.
Sometimes the "Do you trust this computer" setting flashes on the phone and disappears before I can click anything.
How can I fix this?
Sometimes I get the Software Update dialogue in macOS. After approx. 2 minutes it shows the following:
For some reason the issue disappeared for a while but is back now. Disabling "Settings" > "Touch ID & Passcode" > "USB Accessoires" seems like it makes the problem a bit less bad, but not go away.
This is driving me crazy. I upgraded to Mojave 10.14.3 mostly to get rid of the issue. It persists. Some more random information: Before logging in (Filevault pre-boot authentication), the phone will charge fine. Only when a user account is loaded, the issue appears. The likelihood of a successful connection increases with the battery state of the iPhone. Workaround 2 in my answer below suggest that this a "Trust issue" from the iPhone's side. I suppose the solution will have to be hidden somewhere there...
What I tried so far (will update):
- Reset Privacy settings on iPhone
- Different (original, almost new Apple) lightning cables
- "Disable unless needed" option for USB
- Remove and add "iPhone USB" in Network Settings
- Change and remove Thunderbold Bridge in Network Settings
- SMC reset (thanks Jack3231), PRAM reset
- Upgrade to latest iOS 12.4 and MacOS 10.14.6