Adobe Reader asking to accept licence agreement in Thunderbird

Problem

When trying to open a PDF file in Thunderbird you get the message “you must first accept the licence agreement”. Normally you will have agreed to this when you first started Adobe Reader after installing it.

Cause

The Plug-in for Adobe Reader has not detected that the license agreement has been accepted.

Solution

1. In Thunderbird, click Tools (at the top) -> Add-ons -> Plug-ins.
2. In this section, find the Adobe Reader plug-in.
3. Disable and then Enable the plug-in. This will cause the program to recognise you have already accepted the agreement.