Everything worked fine until I upgraded to 128.3.1 Now I cannot open any attachments. The most urgent to fix is pdf attachments. I am running Thunderbird in Ubuntu and the default app in my Ubuntu is Okular. Under Thunderbird Settings, Files and Attachments, the pdf setting is currently System Handler but that does not lead to any action when I click on an attachment. Under Thunderbird Settings, there are no apps listed in the Other list. Selecting that option just takes me to Ubuntu Documents - where there are no apps. Okular is definitely the default app in my Ubuntu setup for opening pdf files. How do I get Thunderbird to use this? Thanks for your help Ian