Comment 15 for bug 1981163

UPDATE: PLEASE READ

In THUNDERBIRD
Change the Preferences again as i'm putting them back to where they should be.
Files & Attachments
Firefox HTML Document reset back to use 'Firefox default' as it cannot remain using the 'Adobe Acrobat'
PDF still set to use Adobe Acrobat default

In FIREFOX
Access Settings/Preferences - about:preferences
Files & Attachments
It has Portable Document - PDF to open in Firefox so set to use 'Adobe Acrobat'

Back in Thunderbird' reopen Draft - Edit - get Write compose windwo - click on attachment pdf and it is now opening in 'Adobe Acrobat'

REset Firefox settings - about:preferences
Files & Attachments
It has Portable Document - PDF - reset back to open in Firefox - (I like online pdf opening in firefox tab)

Back in new Write window - add attachment pdf - double click to open and it is now using Adobe Acrobat.
Error console still produces same error.

I'm not sure whether setting:
THUNDERBIRD - Change the Preferences
Files & Attachments
Firefox HTML Document from Firefox to Adobe Acrobat
testing opening of pdf
Then resetting it back to say Action: Firefox default
Seems to be fixing the issue

OR
whether after doing the above - I then changed the settings in Firefox -
PDF to use Adobe Acrobat
testing opening of pdf
Then resetting it back to say Action: Firefox default

But whether it was doing it in Thunderbird or a combination of both I'm now getting those attachments opening in Adobe