iPhone tethering not working via bluetooth

Solution 1:

This fixes what i presume to be a corrupt internet sharing preference file. It will also remove all other network settings such as wifi access-points and their passwords so keep that in mind. Other data such as pictures and contacts will be completely safe.

1. On your iPhone, go to Settings -> General -> Reset and choose Reset Network Settings.
2. The iPhone will ask you to confirm and then restart.
3. In Settings -> Internet Sharing reenable it and choose to turn on bluetooth if a dialog asking to do so appears.
4. Reconnect to your wifi-network if applicable.
5. You're probably done, try connecting. If it doesn't work go on.
6. In Settings -> General -> Bluetooth tap the blue arrow beside your computer and choose to forget the device.
7. On your computer go to System Preferences -> Bluetooth and remove your iPhone from the list.
8. Go to System Preferences -> Network. In the Location drop down choose Edit Locations.... Add a new location and press done.
9. Make sure the new location is selected and press Apply.
10. Go back to System Preferences -> Bluetooth and re-pair your phone to the computer.
11. Connect to your iPhone's bluetooth network.
12. Back in System Preferences -> Network if you do not have a Bluetooth PAN interface add it by pressing the + button in the lower left.
13. Press Apply and cross your fingers.

Doing the first five solved it for me, after one year of broken bluetooth-tethering.

Solution 2:

After the iPhone 5 wouldn't connect after pairing, and before I did all this, I powered the i Phone5 down and powered it up again. Magically it worked with nothing further required.