Bluetooth connection error: Can't connect to Apple Magic Trackpad 2

I have a MacBook Pro (13-inch, 2016) running Mojave 10.14.3 (18D42) that won't connect to an Apple Magic Trackpad 2 over Bluetooth.

The trackpad appears in my Bluetooth menu, and I can connect to it via a cable, but not using Bluetooth. The trackpad is charged (I see this when connecting cable).

The following is what I think are the relevant parts from the system log. It appears to me that it starts to connect, but then something goes wrong. There's something about deviceDestroyed at 09:05:25.700012, an error getting the remote name at 09:05:25.712184, and then  BluetoothHCIAuthenticationRequested failed because not connected at 09:05:25.712967.

I've had this problem for a while, also often with my wireless keyboard, but today the Bluetooth connection to the keyboard works.

So the forum complains that the post is too long when I include the log. I'll try to include it in a comment after posting.

Any assistance appreciated.