Go to the attachments tab in preferences and delete the entry there for handling PDF files.

After removing this entry in preferences the error on opening a pdf remains....

Then it is not a Thunderbird issue. Thunderbird writes the file and passes the name to the operating system to open when there is no helper registered.

Here the issue is a missing file.

Where does your temp environment variable point to? I would expect the file to be in /tmp/test.PDF not /tmp/mozilla_jan0/test.PDF I really have no idea where this mozilla_jan0 sub folder is coming from.

The issue is not a missing file as the file is present (for a while) in folder /tmp/mozilla_username0. The folder seems to be created by Mozilla and contains all attached files with any extension. There is no environment variable pointing to this folder. The issue seems to be the pdf reader who cannot read files outside the home folder. On the other side image apps, doc apps, etc have no problem to open and read their files in /tmp/mozilla_username0.

Matt said

Go to the attachments tab in preferences and delete the entry there for handling PDF files.

I found that you had to change Preview in Attachments to open in Preview, rather than delete entry as, there is no way of deleting entry under incoming attachments. How the setting had changed by itself I have no idea, but it works properly now so thanks for heading me in the right direction. :)

hughmoz said

Matt said

Go to the attachments tab in preferences and delete the entry there for handling PDF files.

I found that you had to change Preview in Attachments to open in Preview, rather than delete entry as, there is no way of deleting entry under incoming attachments. How the setting had changed by itself I have no idea, but it works properly now so thanks for heading me in the right direction. :)

Pleased you found your solution. But deleting is as simple as selecting the entry and using the key on your keyboard marked with the word Delete.

I thought that you could not delete in that box as, if you right click on it there are no choices given, however, I tried highlighting it and then back-spacing and it did delete, and it still works so, you are correct. However, not everyone will realise that you can delete it unless you explain the process completely. It's just as quick to put preview in the drop-down menu under Preview in that attachments box :)