lncli addinvoice fails with "permission denied"

[merehap]

Background

There are two issues here:

1. lncli addinvoice fails.
2. The error message given is not very helpful.

Here's the command that I ran:
./lncli addinvoice --amt 2000
[lncli] rpc error: code = Unknown desc = permission denied

I suspect that the failure might be related to me upgrading my version of lnd.

Your environment

• version of lnd
  lnd version 0.4.2-beta commit=7c2307984d38ed5a27f27798f30aacb619927454
• which operating system (uname -a on *Nix)
  Raspbian
  Linux 4.9.80-v7+ make check error #1098 SMP Fri Mar 9 19:11:42 GMT 2018 armv7l GNU/Linux
• version of btcd, bitcoind, or other backend
  Bitcoin Core Daemon version v0.16.99.0-9b8b1079d
• any other relevant environment details

Steps to reproduce

Unknown, but potentially something like the following:

1. Upgrade for lnd 0.4.1 to 0.4.2.
2. Run lncli addinvoice --amt 2000

Expected behaviour

• A new invoice is generated.
• If a permissions error occurs, information about the resource in question is provided (e.g. the file path of the wrongly-permissioned file, so that the user can manually fix the permissions).

Actual behaviour

• No invoice is generated.
• An error occurs.
• The error message is not helpful enough (does not include a file path, for example).

[Roasbeef]

You need to delete your old set of macaroons, as there's now a new invoice.macaroon.