Problem with parameter mail.compose.attach.dir

[Angel1970Spain]

I want report a problem with conf parameter mail.compose.attach.dir
When I attach a file from my external hd the conf of thunderbird save the last address in the parameter, and when I try to attach new file without the exterar hd connected the function not execute and nothing happens.
Simply baffling.
Can you fix that error?
Thank you in advance

[Agentvirtuel]

Bonjour

Is it this similar discussion thread.
https://connect.mozilla.org/t5/discussions/quot-attach-quot-button/td-p/141782